One of the more insidious malware attacks in recent months as been an attack that disguises itself as an antivirus program. It appears on your system as ‘XP Antivirus’, which is not a real product. It then usually flashes up a fake virus detection notice such as this:
And then tries to get you to purchase the software or updates, thus providing your credit card details to some rogue organization. In addition, the virus usually embeds itself deeply into your system software, making it difficult to remove. It may also monitor keystrokes and steal other personal data.
If you start encountering antivirus warnings from a program you are not familar with, you should have your system checked immediately.
You can also do a cursory check of your system following the steps outlined in our Support article: Spyware/Virus Detection.