Scareware is the name given to software that warns users about non-existent problems with their computer that, it is promised, can be fixed by buying a security product. The criminals are trying to trick you into providing your payment details. The product they sell you is usually ineffective or, sometimes, actively harmful in that it contains a computer virus itself. Two examples of scareware messages are given below. If you receive such a message shut down your computer (even clicking the cancel button on the fake software could be dangerous).
This software just gets more and more sophisticated - see here for some more examples of fake security software and how it affects your computer.
WBS uses Microsoft Forefront for its antivirus protection. If you receive a security warning from any other software be very wary and contact the Helpdesk for advice.
Fake Security Product 1
Fake Security Product 2
If you think your home computers has been infected you can obtain a free online scan at http://housecall.trendmicro.com/ . If you don't already have anti-virus software installed on your computer you can get a free, and very effective product available from http://www.microsoft.com/security_essentials/