Download the following three programs:
http://www.spybot.info/en/spybotsd/index.htmlhttp://www.javacoolsoftware.com/spywareblaster.htmlhttp://www.lavasoftusa.com/software/adaware/Install them, then disonnect from the Internet, and stat your computer in safe mode (press the restart buttin and hit the F8 key while it is booting up to go into safe mode). Once in safe mode run a scan with all three programs, reboot in "normal" mode, make sure you have the latest Windows Updates, and make sure your AntiVirus program is up to date.