This is most likely the MS Blaster worm. You need to update your system and
follow MS' recommended steps, which are here:
http://www.microsoft.com/security/incident/blast.asp
A removal tool is available at this site also.
**********************************************************

I recently built a PC with MSI865PE Neo2-LS mobo and Windows XP .  The
following message comes intermittently shutting down the system with the
following message....

System Shutdown
The system is shutting down.  Please save all work in progress and log off.
Any unsaved changes will be lost.  The shutdown was initiated by NT
AUTHORITY\SYSTEM
Message
Windows must now restart because the Remote Procedure Call (RPC) service
terminated unespectedly.

              The NOSPIN Group is now offering Free PC Tech
                     support at our newest website:
                          http://freepctech.com