This onemight help:

Article ID : 156669
Last Review : September 5, 2007
Revision : 4.3

How to troubleshoot a "STOP 0xC000021A" error
http://support.microsoft.com/kb/156669
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Rey


"Heidi" wrote:

> When I turn my computer on, I get a winlogon.exe error message. Then when I
> turn off the computer, it automatically restarts, and I have to shut down
> twice to get it to turn off.
>
> I disabled "automatically restart" so that I could see what error message I
> receive. I now get "Fatal System Error Stop c000021a".
>
> I'm not sure what to do now. Any help would be appreciated.