I am having a very similar problem in that
1 i keep getting popup ads inspite of a popup blocker
2. If I search on google I get redirected to another Ad site ( via a couple of quick redirects eg
http://www.google.com/search?hl=en&q=argos&btnG=Search&aq=f&oq=&aqi=
goes
http://www.blackmoonpoker.com/pokerboat/index.php?lang=gb
http://159_48664.admarketplace.com/
I tried your suggestion to go to Malwarebytes and my browser ( IE) took me to google site for this search and wont take me anywhere else!
It looks like malware ads but the ad sites are in the main quite "respectable" I see site like overture on the way and I suspect a yahoo virus but find that incredible.
Given that this problem blocks me from a google search solution does anyone know how to fix it
Im about to rebuilsd my computer from scratch softwarewise but would rather not!