Do what BLAKE said. Most hijacking fake-virus programs will not allow you to run Windows Defender, your anti-virus program, or your Ad-aware programs. Here's a page that shows you how to do this (do this from a working computer): http://www.bleepingcomputer.com/virus-removal/remove-antivirus-vista-2010 (there are variations of the same virus/trojan) I know 'cuz I just did it RIGHT NOW. I cleaned the same PC that I cleaned WAY BACK with a DELL system restore.
