BSOD Fix: STOP: c000021a The Windows Logon Process system process terminated unexpectedly with a status

you get a BSOD like this when you boot your Windows XP:
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.
 
Microsoft suggest this article with step-by-step instructions:
http://support.microsoft.com/kb/156669/en-us
 
I've found it easier to fix by booting using ERD Commander 2007 and using the System File Repair Wizard.
it will scan your Windows folder and will repair the corrupted files. the process takes less than 5 minutes and you're up and running again.
 
it is advised to run a disk scan like Chkdsk, to make sure the problem didn't raised because of a HD problem. in most cases the cause is unsuccessful updates/installations.
 
Good Luck,
Yaron