This hasn't shown up on any news sites yet that I know of but there is a really nasty worm going around the net that uses an exploit in RPC on XP. Make sure you have the latest updates to Windows XP installed or you will get zapped by this at some point.

It will cause a crash in RPC which will force your machine to reboot 60 seconds later (With a count down). It's a PITA to remove too once you get it.