A fake anti virus program may first appear as a legitimate looking pop-up window that tells the user that they have a dangerous virus. They are then prompted to click to buy anti virus protection to sort out their system. There is, however, no virus at all but the advert contains a potential problem if the user then clicks on it.
DONT CLICK ON IT:
The best solution is to turn off your computer (hard shut down) so the fake program wont install. Yes you will lose whatever you were working on, but its much better than getting a virus.
WHAT IF ITS TOO LATE:
Call me or email me, and ill see if I can help.