Fake Infection Warnings Can Be Real Trouble

Michael Vana knew something was up when he saw the pop-up from "Antivirus 2009" in the middle of his screen. The former Northwest Airlines avionics technician guessed that the dire warning of a system infection was fake, but when he clicked on the X to close the window, it expanded to fill his screen. To get rid of it, he had to shut down his PC.

Sound familiar? Dirty tricks like these, designed to get you to install and buy fake antivirus products, are more common than ever.