I always get a System Shutdown error from NT System Authority which shuts my computer down after so many seconds and restarts. How do I fix this problem? It says something about an error has occured in lsass.exe. How do I fix this problem?

Those are signs of the famous Sasser worm virus with lsass.exe shutting down after being exploited. However, I’m unaware of Sasser affecting server 2003 so I’m a little confused here. Can you confirm you’re running 2003 and not 2000?

Yes I am running windows server 2003 enterprise edition.

Sasser was a LOW risk on 2003 however variants of the sasser has had a greater effect on 2003 server.

Boot to safe mode and run a full virus scan.

well my anti virus is not detecting as a virus ?

well my anti virus is not detecting as a virus ?

Is it always the lsass.exe service? I've had a similar problem in the past where the same service kept failing, and the problem was my hard drive. The file was located on a bad block. Have you run chkdisk at boot? Unlikely to be the solution, but worth a shot.