I assume you've already run your antivirus to scan your computer, so I second what someone said about AdBlock Plus.
Also, use something like CCleaner to clean out your cache and temporary files and other spare junk; something may be hiding in there :/

AdBlock http://download.cnet.com/1770-20_4-0.html?query=adblock+plus&tag=srch&searchtype=downloads&filterName=platform%3DWindows&filter=platform%3DWindows

CCleaner http://download.cnet.com/ccleaner/

I hope you can get it all sorted out! :/