SpyBot Search & Destroy
http://www.spybot.info/en/download/index.html
Use SpyBot to find and remove Spyware, Malware, etc.
After Install and on first use you must Search for Updates. Then, use the Check for problems button to start scan of your computer.
Problems are not displayed until the scan is almost complete. So while you’re waiting for something to happen, you’re thinking, my computer has no spyware installed. But be patient and you’ll find out what is really going on behind the scenes on your PC.