Windows xp not open

To repair missing or corrupted system file/s, boot up with the Windows installation CD then - Press R to repair when instructed. Press 1 or Enter to repair the C:\Windows folder. Then type chkdsk /r and then press Enter. The repair process will take quite a long time.

Well this means one of important files needed to start Windows is corrupted (it's a registry file).
I'd recommend repairing Windows installation. If you have Windows XP and also the Original Windows CD follow: this guide.

It is a registry problem.
Follow instructions from this link:

Issue:NTOSKRNL.EXE is missing or corrupt.
Related errors:
Below is a listing of the full error message that may be related to this error.
Windows NT could not start because the below file is missing or corrupt:
C:\Winnt\System32\Ntoskrnl.exe
Cause:

1. Keyboard issue
2. Miscellaneous corruption
3. Corrupt boot.ini file.
4. Missing boot.ini file.
5. Missing or corrupt ntoskrnl.exe file.
6. Windows NT installed on a partition bigger then 7.8GB
7. Corrupted hard disk drive or severely corrupted Windows.

Solution:Keyboard issue
This issue has also been known to be caused by a short in the ground wire in the keyboard cable. Make sure this is not the cause of your error by replacing the keyboard with a different keyboard or simply just disconnecting the keyboard from the computer.
Miscellaneous corruption
Before trying any of the below recommendations it's recommend that you attempt to load the last known good configuration. Additional information about doing this can be found on document CH000626.
Corrupt boot.ini file
This issue is often caused when the boot.ini is missing or improperly configured. This issue often arises after a user has recently added or removed an operating system on the computer or added or removed hard disk drives in the computer.
Make sure the line pointing to the operating system and its drive and partition is properly configured in the [boot loader] and [operating systems] section. Additional information about boot.ini can be found on document CH000492.
Missing boot.ini file
Microsoft Windows XP users:
If the boot.ini is severely corrupted or missing a user running Microsoft Windows XP can rebuild the boot.ini to resolve this issue. Additional information about rebuilding the boot.ini can be found on document CH000648.
Microsoft Windows NT and Windows 2000 users:
To restore the original boot.ini file in Microsoft Windows NT or Windows 2000 you will need an ERD and follow the below steps. If you do not have an ERD you will be unable to follow these steps.

1. Boot the computer with your Windows NT three setup diskettes or the Windows 2000 setup disc.
2. In the setup menu, type R to start the repair.
3. When prompted for the ERD diskette insert the diskette and inspect the startup environment.

Missing or corrupt ntoskrnl.exe file
If the ntoskrnl.exe file is corrupt or missing this can also generate the error. To restore this file follow the below steps.

1. Insert the Microsoft Windows XP CD. Note: If you have a recovery CD or a restore CD and not a Microsoft Windows XP CD it is likely the below steps will not resolve your issue.
2. Reboot the computer, as the computer is starting you should see a message to press any key to boot from the CD. When you see this message press any key.
3. In the Microsoft Windows XP setup menu press the R key to enter the recovery console.
4. Select the operating system you wish to fix, and then enter the administrator password.
5. Type expand d:\i386\ntoskrnl.ex_ c:\windows\system32
6. You will then be prompted if you wish to overwrite the file type Y and press enter to overwrite the file.
7. Type exit to reboot the computer.

Windows NT installed on a partition bigger then 7.8GB
If you are running Microsoft windows NT 4.0 on a partition larger than 7.8GB this issue can occur if the boot files are located outside this limitation. When this error occurs your computer will have the error message as shown below.
OS Loader v4.01
Disk I/O error status=00000001
Windows NT could not start because the below file is missing or corrupt: winnt\system32\Ntoskrnl.exe
Please reinstall a copy of the above file.
If your system partition is larger than 7.8GB you will need to delete the partition and recreate the partition to 7.8GB or less. Additional information about this issue can be found on Microsoft KB Q224526.
Corrupted hard disk drive or severely corrupted Windows
Attempt to check the hard disk drive for any errors by running the chkdsk program. To do this follow the below steps.

1. Insert the Microsoft Windows XP CD. Note: If you have a recovery CD or a restore CD and not a Microsoft Windows XP CD it is likely the below steps will not resolve your issue.
2. Reboot the computer, as the computer is starting you should see a message to press any key to boot from the CD. When you see this message press any key.
3. In the Microsoft Windows XP setup menu press the R key to enter the recovery console.
4. Select the operating system you wish to fix, and then enter the administrator password.
5. Once at the recovery console type chkdsk /r
6. Once completed type exit and see if issue is resolved.

If after trying all of the above steps you are still encountering the same issue it's likely that Windows is severely corrupted and it is recommended you attempt to reinstall Windows. Additional information about erasing the computer and starting over can be found on document CH000186.
Finally, if during the Windows installation you encounter errors it's likely that your hard disk drive is bad.

Issue: NTOSKRNL.EXE is missing or corrupt.
Related errors:
Below is a listing of the full error message that may be related to this error.
Windows NT could not start because the below file is missing or corrupt:
C:\Winnt\System32\Ntoskrnl.exe
Cause:

1. Keyboard issue
2. Miscellaneous corruption
3. Corrupt boot.ini file.
4. Missing boot.ini file.
5. Missing or corrupt ntoskrnl.exe file.
6. Windows NT installed on a partition bigger then 7.8GB
7. Corrupted hard disk drive or severely corrupted Windows.

Solution: Keyboard issue This issue has also been known to be caused by a short in the ground wire in the keyboard cable. Make sure this is not the cause of your error by replacing the keyboard with a different keyboard or simply just disconnecting the keyboard from the computer.
Miscellaneous corruption Before trying any of the below recommendations it's recommend that you attempt to load the last known good configuration. Additional information about doing this can be found on document CH000626.
Corrupt boot.ini file This issue is often caused when the boot.ini is missing or improperly configured. This issue often arises after a user has recently added or removed an operating system on the computer or added or removed hard disk drives in the computer. Make sure the line pointing to the operating system and it's drive and partition is properly configured in the [boot loader] and [operating systems] section. Additional information about boot.ini can be found on document CH000492.
Missing boot.ini file Microsoft Windows XP users: If the boot.ini is severely corrupted or missing a user running Microsoft Windows XP can rebuild the boot.ini to resolve this issue. Additional information about rebuilding the boot.ini can be found on document CH000648. Microsoft Windows NT and Windows 2000 users: To restore the original boot.ini file in Microsoft Windows NT or Windows 2000 you will need an ERD and follow the below steps. If you do not have an ERD you will be unable to follow these steps.

1. Boot the computer with your Windows NT three setup diskettes or the Windows 2000 setup disc.
2. In the setup menu, type R to start the repair.
3. When prompted for the ERD diskette insert the diskette and inspect the startup environment.

Missing or corrupt ntoskrnl.exe file If the ntoskrnl.exe file is corrupt or missing this can also generate the error. To restore this file follow the below steps.

1. Insert the Microsoft Windows XP CD. Note: If you have a recovery CD or a restore CD and not a Microsoft Windows XP CD it is likely the below steps will not resolve your issue.
2. Reboot the computer, as the computer is starting you should see a message to press any key to boot from the CD. When you see this message press any key.
3. In the Microsoft Windows XP setup menu press the R key to enter the recovery console.
4. Select the operating system you wish to fix, and then enter the administrator password.
5. Type expand d:\i386\ntoskrnl.ex_ c:\windows\system32
6. You will then be prompted if you wish to overwrite the file type Y and press enter to overwrite the file.
7. Type exit to reboot the computer.

Windows NT installed on a partition bigger then 7.8GB If you are running Microsoft windows NT 4.0 on a partition larger than 7.8GB this issue can occur if the boot files are located outside this limitation. When this error occurs your computer will have the error message as shown below. OS Loader v4.01
Disk I/O error status=00000001
Windows NT could not start because the below file is missing or corrupt: winnt\system32\Ntoskrnl.exe
Please reinstall a copy of the above file. If your system partition is larger than 7.8GB you will need to delete the partition and recreate the partition to 7.8GB or less. Additional information about this issue can be found on Microsoft KB Q224526.
Corrupted hard disk drive or severely corrupted Windows Attempt to check the hard disk drive for any errors by running the chkdsk error. To do this follow the below steps.

1. Insert the Microsoft Windows XP CD. Note: If you have a recovery CD or a restore CD and not a Microsoft Windows XP CD it is likely the below steps will not resolve your issue.
2. Reboot the computer, as the computer is starting you should see a message to press any key to boot from the CD. When you see this message press any key.
3. In the Microsoft Windows XP setup menu press the R key to enter the recovery console.
4. Select the operating system you wish to fix, and then enter the administrator password.
5. Once at the recovery console type chkdsk /r
6. Once completed type exit and see if issue is resolved.

If after trying all of the above steps you are still encountering the same issue it's likely that Windows is severely corrupted and it is recommended you attempt to reinstall Windows. Additional information about erasing the computer and starting over can be found on document CH000186. Finally, if during the Windows installation you encounter errors it's likely that your hard disk drive is bad.

NTOSKRNL.EXE is missing or corrupt.

Related errors:

Below is a listing of the full error message that may be related to this error.

Windows NT could not start because the below file is missing or corrupt:
C:\Winnt\System32\Ntoskrnl.exe

Cause:
Keyboard issue
Miscellaneous corruption
Corrupt boot.ini file.
Missing boot.ini file.
Missing or corrupt ntoskrnl.exe file.
Windows NT installed on a partition bigger then 7.8GB
Corrupted hard disk drive or severely corrupted Windows.
Solution:
Keyboard issue
This issue has also been known to be caused by a short in the ground wire in the keyboard cable. Make sure this is not the cause of your error by replacing the keyboard with a different keyboard or simply just disconnecting the keyboard from the computer.

Miscellaneous corruption
Before trying any of the below recommendations it's recommend that you attempt to load the last known good configuration. Additional information about doing this can be found on document CH000626.

Corrupt boot.ini file
This issue is often caused when the boot.ini is missing or improperly configured. This issue often arises after a user has recently added or removed an operating system on the computer or added or removed hard disk drives in the computer.
Make sure the line pointing to the operating system and it's drive and partition is properly configured in the [boot loader] and [operating systems] section. Additional information about boot.ini can be found on document CH000492.

Missing boot.ini file
Microsoft Windows XP users:
If the boot.ini is severely corrupted or missing a user running Microsoft Windows XP can rebuild the boot.ini to resolve this issue. Additional information about rebuilding the boot.ini can be found on document CH000648.

Microsoft Windows NT and Windows 2000 users:

To restore the original boot.ini file in Microsoft Windows NT or Windows 2000 you will need an ERD and follow the below steps. If you do not have an ERD you will be unable to follow these steps.
Boot the computer with your Windows NT three setup diskettes or the Windows 2000 setup disc.
In the setup menu, type R to start the repair.
When prompted for the ERD diskette insert the diskette and inspect the startup environment.
Missing or corrupt ntoskrnl.exe file
If the ntoskrnl.exe file is corrupt or missing this can also generate the error. To restore this file follow the below steps.
Insert the Microsoft Windows XP CD. Note: If you have a recovery CD or a restore CD and not a Microsoft Windows XP CD it is likely the below steps will not resolve your issue.
Reboot the computer, as the computer is starting you should see a message to press any key to boot from the CD. When you see this message press any key.
In the Microsoft Windows XP setup menu press the R key to enter the recovery console.
Select the operating system you wish to fix, and then enter the administrator password.
Type expand d:\i386\ntoskrnl.ex_ c:\windows\system32
You will then be prompted if you wish to overwrite the file type Y and press enter to overwrite the file.
Type exit to reboot the computer.
Windows NT installed on a partition bigger then 7.8GB
If you are running Microsoft windows NT 4.0 on a partition larger than 7.8GB this issue can occur if the boot files are located outside this limitation. When this error occurs your computer will have the

error message as shown below.

OS Loader v4.01
Disk I/O error status=00000001
Windows NT could not start because the below file is missing or corrupt: winnt\system32\Ntoskrnl.exe
Please reinstall a copy of the above file.

If your system partition is larger than 7.8GB you will need to delete the partition and recreate the partition to 7.8GB or less. Additional information about this issue can be found on Microsoft KB Q224526.

Corrupted hard disk drive or severely corrupted Windows
Attempt to check the hard disk drive for any errors by running the chkdsk error. To do this follow the below steps.

Insert the Microsoft Windows XP CD. Note: If you have a recovery CD or a restore CD and not a Microsoft Windows XP CD it is likely the below steps will not resolve your issue.
Reboot the computer, as the computer is starting you should see a message to press any key to boot from the CD. When you see this message press any key.
In the Microsoft Windows XP setup menu press the R key to enter the recovery console.
Select the operating system you wish to fix, and then enter the administrator password.
Once at the recovery console type chkdsk /r
Once completed type exit and see if issue is resolved.
If after trying all of the above steps you are still encountering the same issue it's likely that Windows is severely corrupted and it is recommended you attempt to reinstall Windows. Additional information about erasing the computer and starting over can be found on document CH000186.
Finally, if during the Windows installation you encounter errors it's likely that your hard disk drive is bad.

Issue: NTOSKRNL.EXE is missing or corrupt.
Related errors:
Below is a listing of the full error message that may be related to this error.
Windows NT could not start because the below file is missing or corrupt:
C:\Winnt\System32\Ntoskrnl.exe
Cause:

1. Keyboard issue
2. Miscellaneous corruption
3. Corrupt boot.ini file.
4. Missing boot.ini file.
5. Missing or corrupt ntoskrnl.exe file.
6. Windows NT installed on a partition bigger then 7.8GB
7. Corrupted hard disk drive or severely corrupted Windows.

Solution: Keyboard issue This issue has also been known to be caused by a short in the ground wire in the keyboard cable. Make sure this is not the cause of your error by replacing the keyboard with a different keyboard or simply just disconnecting the keyboard from the computer.
Miscellaneous corruption Before trying any of the below recommendations it's recommend that you attempt to load the last known good configuration. Additional information about doing this can be found on document CH000626.
Corrupt boot.ini file This issue is often caused when the boot.ini is missing or improperly configured. This issue often arises after a user has recently added or removed an operating system on the computer or added or removed hard disk drives in the computer. Make sure the line pointing to the operating system and it's drive and partition is properly configured in the [boot loader] and [operating systems] section. Additional information about boot.ini can be found on document CH000492.
Missing boot.ini file Microsoft Windows XP users: If the boot.ini is severely corrupted or missing a user running Microsoft Windows XP can rebuild the boot.ini to resolve this issue. Additional information about rebuilding the boot.ini can be found on document CH000648. Microsoft Windows NT and Windows 2000 users: To restore the original boot.ini file in Microsoft Windows NT or Windows 2000 you will need an ERD and follow the below steps. If you do not have an ERD you will be unable to follow these steps.

1. Boot the computer with your Windows NT three setup diskettes or the Windows 2000 setup disc.
2. In the setup menu, type R to start the repair.
3. When prompted for the ERD diskette insert the diskette and inspect the startup environment.

Missing or corrupt ntoskrnl.exe file If the ntoskrnl.exe file is corrupt or missing this can also generate the error. To restore this file follow the below steps.

1. Insert the Microsoft Windows XP CD. Note: If you have a recovery CD or a restore CD and not a Microsoft Windows XP CD it is likely the below steps will not resolve your issue.
2. Reboot the computer, as the computer is starting you should see a message to press any key to boot from the CD. When you see this message press any key.
3. In the Microsoft Windows XP setup menu press the R key to enter the recovery console.
4. Select the operating system you wish to fix, and then enter the administrator password.
5. Type expand d:\i386\ntoskrnl.ex_ c:\windows\system32
6. You will then be prompted if you wish to overwrite the file type Y and press enter to overwrite the file.
7. Type exit to reboot the computer.

Windows NT installed on a partition bigger then 7.8GB If you are running Microsoft windows NT 4.0 on a partition larger than 7.8GB this issue can occur if the boot files are located outside this limitation. When this error occurs your computer will have the error message as shown below. OS Loader v4.01
Disk I/O error status=00000001
Windows NT could not start because the below file is missing or corrupt: winnt\system32\Ntoskrnl.exe
Please reinstall a copy of the above file. If your system partition is larger than 7.8GB you will need to delete the partition and recreate the partition to 7.8GB or less. Additional information about this issue can be found on Microsoft KB Q224526.
Corrupted hard disk drive or severely corrupted Windows Attempt to check the hard disk drive for any errors by running the chkdsk error. To do this follow the below steps.

1. Insert the Microsoft Windows XP CD. Note: If you have a recovery CD or a restore CD and not a Microsoft Windows XP CD it is likely the below steps will not resolve your issue.
2. Reboot the computer, as the computer is starting you should see a message to press any key to boot from the CD. When you see this message press any key.
3. In the Microsoft Windows XP setup menu press the R key to enter the recovery console.
4. Select the operating system you wish to fix, and then enter the administrator password.
5. Once at the recovery console type chkdsk /r
6. Once completed type exit and see if issue is resolved.

If after trying all of the above steps you are still encountering the same issue it's likely that Windows is severely corrupted and it is recommended you attempt to reinstall Windows. Additional information about erasing the computer and starting over can be found on document CH000186. Finally, if during the Windows installation you encounter errors it's likely that your hard disk drive is bad.

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this problem occurs when you try to update drivers in the computer..sometimes windows XP cannot update the driver and that corrupts system.ini file as it has a lot of bad entries..Due to this you will get this error mesage..No its not due to virus.its due to an attempt to change system.ini file

Windows could not start because the following file is missing or corrupt: \WINDOWS\SYSTEM32\CONFIG\SYSTEM

That means the System Registry Hive has become corrupted.

There are two ways to get back up and running. The easy way which doesn't always work, and then there is the hard way.

Easy Way --- Note that this doesn't always work.
When you are booting your system, press the F8 key during the start of the bootup sequence, meaning after it does the Power On Self Test.

Once you press the F8 key, you will be taken to a Menu. Select "Boot Using Last Known Good Configuration".

It will now attempt to load Windows XP using a past set of configuration files.

If that doesn't work, there is the next step....the hard way.

Hard Way
Boot your system with the Windows XP Install CD, let the system boot into the Setup. Once in the Setup, choose to run the Recovery Console.

You will now be presented with a screen similar to good old DOS.

First, we will recover the System Hive.

Now, type in the following commands with pressing Enter after each line.

md tmp
copy C:\windows\system32\config\system C:\windows\tmp\system.bak
delete C:\windows\system32\config\system
copy C:\windows\repair\system C:\windows\system32\config\system

Be very careful when you are typing in these commands, one wrong move, and you have, broken Windows XP.

Also, change the C in the commands to whatever your Windows XP drive letter is.

Attempt to boot the system, if it doesn't boot, get back into the Recovery Console and do the following commands.

md tmp
copy C:\windows\system32\config\software C:\windows\tmp\software.bak
delete C:\windows\system32\config\software
copy C:\windows\repair\software C:\windows\system32\config\software