Hi,

The last time i saw something like this was Windows RPC message popped up and say Windows will restart in 20 seconds.................and the reason for that was Blaster Worm( there are a few other Worms or malwares known to do the same ) ......................have you Updated the system with all the Microsoft Critical Updates ?

meanwhile If it is the RPC Info on How to stop your Computer form restarting and some Info on RPC itself

hope it helps

--Good Luck--