Shutdown Unexpectedly, Please help ..

hello sir/medum,

When i connect to internet after some time one window opens named “system shutdown” with having red into mark having the information of
“This system is shuting down. please save all work in progras and logoff. any unsaved data will lost.This shutdown was initiated by NT AUTHORITY\System”

Thime before shutdown: 00:00:60

Message: windows must now restart because the remote procedure call(rpc) service terminated unexectedly”

I am using windows Xp version.This problem make me upset. please help.How should i fix this.

I am waiting for u r reply

Bye