Stupid malware...happened to my pc not too long ago...it's a bogus "virus" that you pay the company who is asking you to buy their antivirus software from to "remove." What I did was just restart my computer in safe-mode then restored the hard drive to a previous date (system restore). That did the trick...I've since bought a Mac...
ps. Antivirus Soft was the exact same malware that "infected" my computer! It's a nasty one...won't let you open anything from your normal screen hence the need to restart in safe mode!