"Automatic Shutdown..." WHY???

Thanks to all. Blaster worm has been located and
successfully removed!!

Stephen

-----Original Message-----
Hi, I wonder if there's anybody out there that can help
me.

Recently I've been connecting to the Internet and
sometimes it's been fine but other times I get a message
about 2-3 minutes in saying...

"This system is shutting down. Please save all work in
progress and log off. Any unsaved changes will be
lost.
This shutdown was initiated by NT AUTHORITY\SYSTEM.

Message: Windows must now restart because the Remote
Procedure Call (RPC) service terminated unexpectedly"

At first I thought I'd been infected by the Sasser virus
but I've run the check on the Microsoft site and I
appear
to be clean. Does anyone out there have an idea what is
happening here and know how to prevent it?

Thanks,

Stephen

.