Run a anti-virus scan and if the scan finds virus have them quarantined.
Also check the virus and spyware section (this post should be there really, this is a virus question, not a Windows question, you'll get more answers that way) , i think there are links to downloads like 'Anti-malware' and 'Super anti-spywareware'. Have a good read at the stickeys at the top of that page. Loads of info.