I hear that there has been some 'issue' with the RPC service lately. OK, that's a bad joke, and I apologize for it, despite the fact I didn't write it.
Either way, one of the nasty side effects of said beastie is your computer randomly rebooting. This can make applying the appropriate patches a little difficult (as I found out on a friend's machine last week). While it's not the solution, you can ease this problem by changing the behaviour of the RPC service. (XP solution only, I think)
This will attempt to restart the service, instead of the computer. It gives you a bit more time to install the appropriate patch, and/or clean the virus off.
TTFN - Kent