1) Go to Trend Micro's website and run the free antivirus scan:
http://housecall.trendmicro.com/
2) Download Spybot Search&Destroy, install it and update it, then run a scan of you system and let it fix what it finds. Once fixed immunize the system:
http://www.safer-networking.org/en/download/index.html
3) Also download Lavasoft's Adaware again install and update it then scan your system:
http://www.lavasoftusa.com/support/download/
These are all free tools for personal use, if you need further help with any of them, their respective websites have good documentation to get you going. Hope this helps.
Yahoo has a new pop up blocker with Spyware stopper that I just downloaded over the weekend. I like it so far. I found 82 items on this computer with the Yahoo that McAfee couldn't find! My Ad popups have been reduced to almost none and would be none but I don't have the popup blocker on because some websites links open in another browser and cant if I have it on. I hope this helps.