c000021a {Fatal System Error}: no boot

I am getting the below error message:

“STOP: c000021a {Fatal System Error}
The Windows Logon Process system process terminated unexpectedly with a status of 0xc0000034 (0x00000000 0x0000000). The system has been shutdown.”

I actually left my pc for sometime which was connected to the web. But when I came back then I found a black screen and my pc was not working, so I had to unplug it to shut down the computer. After that I am getting the error and I am not able to boot in XP in any mode. Please help

Have you tried doing a system restore, check the guide here on how to do this - http://support.microsoft.com/kb/307545. Also, you should review your backup policy. Incase you dont backup your important documents on the drive and you email then you are going to have some problem.

The STOP 0xC000021A error occurs when either Winlogon.exe or Csrss.exe fails. When the Windows NT kernel detects that either of these processes has stopped, it stops the system and raises the STOP 0xC000021A error. This error may have several causes. More information can be found here - http://support.microsoft.com/kb/156669

If you are not able to perform all the steps given above then you could try to take the macine to some professional pc repair shop and get it fixed over there at some minimal cost.