Unmountable_boot_volume computer stop its operation

If you receive this error message when you restart the computer for the first time during an upgrade to Windows XP, your original operating system will still work correctly. In some cases, you may see a message that states that the wrong cable is being used. However, you may not see this message on computers that have a fast startup time.

• If the file system is damaged, you can use chkdsk /r command to repair the volume. However, if you use the chkdsk /r command, you may lose some data.
• You will need the Windows startup disks or the Windows installation disk. If you do not have them, contact the computer manufacturer for help in obtaining the disks.
• You will need the administrator password to complete the steps.

Your hard drive is having problem, plz try by formating the hard drive