Hi and welcome to Daniweb. :) You could start off by downloading these programs and scanning your computer with them and letting them fix any problems they find:
Adaware: http://www.lavasoftusa.com
Spybot Search and Destroy: http://www.safer-networking.org/en/index.html
After scanning with those two and fixing whatever problems are found, download Hijackthis. Making sure all other browser windows are closed, scan with hijackthis. Do not fix anything yet. Copy and paste the results here so one of the experts can take a look at it. Also be sure to save hijackthis in its own permanent folder when you download it, not a temporary one. That should get you started until someone else takes a look at your thread. :) Good luck!
**The links are kind of old...they are ones I wrote down when I was fixing my computer...if by some chance they don't work let me know.**