Blues screen ( c000021a {Fatal System Error} ) after uninstalling Windows patch

[Dmitry]

Greetings,

After removing one of the security patches (811493) and
restarting I have a a blue screen c000021a {Fatal System
Error} on my Windows XP Professional Edition version.
Neither Safe mode or Last good configuration or even
Bootup Disk seem to work. Thus, I can't even logon the
system.

Any suggestions how to fix it? I would appreciate it greatly.

Thanks