I have a windows XP OS. Of late everytime I switch on the computer, it flashes a message which reads, "the remote procedure call service terminated unexpectedly" and automatically intiates a shutdown pompted by "NT authority/system."

Hey, welcome to D-A-L

Sounds like the MS Blaster worm, here is more info including how you can get rid of it.

http://securityresponse.symantec.com...oval.tool.html