Shutting Down Message!?

A friend of mine has a very annoying problem. (Now mine!) His Pc keeps on shutting down and this is the message he is getting:


This system is shutting down . Please save all work in progress and log off and any unsaved changes will be lost. This shutdown was initiated by NT Authority/System.
Widows must now re-start because the remote produce call (RPC) service is terminating.

Any good ideas please?? He did wonder if it was the "Latest Virus" But I said he couldn't be that lucky



Regards

Chris