It sounds more like an adware infection there. There's one place you can go to online for a free scan of your system. There's no registration required. Housecall by Trend Micro has this at
http://housecall.trendmicro.com/
There arre some other free programs you can download like the AdAware SE Personal edition found at
http://www.lavasoft.com Grisoft recently bought out Ewido and has released their new AVG Anti-Spyware Free tool along with the latest updated release of the AVG 7.5 free antivirus utility. There are available for immediate download at
http://free.grisoft.com/doc/5390/lng/us/tpl/v5#avg-anti-spyware-free
If you want to post a log and do not have HiJack This you can download the free registry scanner at
http://www.spywareinfo.com/~merijn/programs.php