I have a dimension E521 and when it starts up all it does is take me to a screen that says: A disk read error occurred and it's a black screen with spots ont the screen

Try running the Check Disk Utility.

To run the check disk utility you will need a repair disc ora operating system disc. Put the disc in the cd drive and boot fromit. You want to get to the Dos Command Prompt (Black screen with whiteletters) and type the following command: chkdsk /r
Check disk will run well over an hour or two and you will notice thepercentages going from high to low, this is normal. Let it run tocompletion. Then reboot machine.

If check disk fails to solve your problem you might have to reinstall windows.Try doing a Repair Install that way you don't loose your data, documents,music, pictures, videos or programs.

In windows xp you get to the dos command prompt by selecting R for repair whenthe options appear.

In Vista and Windows 7 you want to get to the recoveryconsole and look down at the bottom of the window for the Dos Command.

http://support.dell.com/support/edocs/systems/dime521/en/SM_EN/parts.htm#wp1461049
Once the cooler is out unscrew the fan and go with it to a pc shop and get an similar one - make sure it has the same number of wires.

Narrow it down to a monitor issue (and fix or replace the monitor in particular) or a PC issue (in which case we're also low on info. about the issue.)

How did you try to get to safe mode. Have to tap F8 continuously for a while as soon as pc starts to boot. Holding key down might not work so it's better if you can keep tapping key quickly. If you have tried several times and can't get it to start in safe mode windows will normally put up an error screen to say windows didn't start properly with a few options. If you see this screen select last known good configuration and it might start to load windows normally if you are lucky.

Hi,

Its seems like your RAM is not working properly, so once you replace the this RAM and check it, you problem should be resolve.

Regards

Ashly

Use ISO startup / recovery disk downloadable from here: http://neosmart.net/blog/2008/windows-vista-recovery-disc-download/

your hard drive has been corrupted due to improper shutdown

Hope this help you...This is in relation to what your error code means, you'll need to check against the list.

• Error 0x00000024 - This problem may occur if there is a conflict between Windows XP SP1 and the display adapter drivers that are currently installed.
• Error 0x00000004 - occurs because your computer processor detected and reported an unrecoverable hardware error to Windows
  
• Error 0x0000007b - occurs if your computer is infected with a boot-sector virus.
  
• Error 0x80004005 - occurs because the account that is being used to access the page does not have access to the HKEY_LOCAL_MACHINE\SOFTWARE\ODBC registry key.
  
• Error 0xc0000005 - occurs because of memory corruption.
  
• Error 0xc0000034 - caused by a missing system file (usually Ntdll.dll in the %systemRoot%\system32 directory.
  
• Error 0xc0000006 - occur if there is not enough free hard disk space on the NTFS-compressed hard disk partition when the SIS filter tries to read compressed back pointer data streams from the SIS volume.
  

Another common reason can be malware and spyware that penetrate to your computer registry and started destroying it... that's why it's so important you fix your registry right now!

trust this help.

2 short, 1 long
BIOS checksum error
1 long, 2 short
Memory test failure (bad memory during memory sizing)

if your num lock key responds, you may have to reseat/change the video card (if you are sure monitor is good). else you need to replace your motherboard.
Getback if you need any clarifications