do this it may work against that fake antivirus crap

(this works on windows XP)
Start
Run
Restore
Double click rstrui.exe (you may not see the .exe part) Click next Click a day that is bolded about a week ago Click next It will reboot on it's own After the reboot click finish and it should be successful. 

You will not lose data but any program you installed from that day picked until today will need to be reinstalled.