Recently some of the most virulent pieces of malware use a combination of technical and social engineering to attack both Mac and Windows users.
Two of the most prevalent are called Mac Defender (Mac) and Desktop Defender 2010 (Windows).
The malware will try to trick the user into giving up their credit card number and other personal information. Disguised as anti-virus software the malware will display alerts stating that your machine is infected with viruses. To make the con more believable the malware will create symptoms that mimic a virus attack such as slowing down your computer, disabling any anti-virus software, and placing explicit popup ads on your desktop. The malware may even try to install real viruses and Trojans into the computer to steal local data or infect other users.
Removal Instructions Below

(via ingego.com)

(via 2-spyware.com)
Removal Instructions
If you find yourself infected with this fake Anti-Virus malware do not enter your credit card or other personal information.
Contact the Service Desk at 617-373-4357 for assistance.
Manual Removal of Windows Desktop Defender 2010
Manual Removal of Mac Defender

