Then make sure to check that you update the anti-virus definition files.
Taken from Vapid2323 via Digg
Are you looking for ways to clean up your computer? As you surf the Internet, you are prone to downloading Trojans, viruses, adverts, cookies, and just a bunch of other random Internet junk. Spybot helps clean your computer of spam, well at least most of it. This is what the website has to say for itself:
Spybot – Search & Destroy detects and removes spyware, a relatively new kind of threat not yet covered by common anti-virus applications. Spyware silently tracks your surfing behavior to create a marketing profile for you that is transmitted without your knowledge to the compilers and sold to advertising companies. If you see new toolbars in your Internet Explorer that you haven’t intentionally installed, if your browser crashes inexplicably, or if your home page has been “hijacked” (or changed without your knowledge), your computer is most probably infected with spyware. Even if you don’t see the symptoms, your computer may be infected, because more and more spyware is emerging. Spybot-S&D is free, so there’s no harm giving it a try to see if something has invaded your computer.
The best part about this program it is easy to use, uses minimal system resources, and its free! What more can you ask for? Check it out here.