Well, mine was a virus that had three different files in System32, and I guess how it worked was they were constantly running checks on each other to make sure they were all still functional. Once you deleted one, the other two would go "Oh snap, we're getting fucked with," and reinstall the deleted file, kinda like that virus in the Brotherhood of Steel bunker in New Vegas.
I ran
Kapersky's AVP Tool for something like a day and it managed to lock down all three of them and delete them simultaneously, along with all the other shit I've picked up from streaming video TV episode link sites. It was totally some super-rad movie hacker shit.