Sounds like you may have a hijacker. Check this thread for suggestions on what to do:
http://www.daniweb.com/techtalkforums/thread5690.html
Also, use Windows Update to get all the critical updates. If you're still having trouble after 'helping yourself,' get HiJackThis from here:
http://www.softpedia.com/progDownload/x-Download-5034.html
Put it in a folder like c:\hjt\hijackthis.exe (don't run if from a temporary folder or from the desktop). Close all windows, scan, save the log, and then post the log in the Security forum along with a description of any remaining problems.
dlh6213
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