go with HiJack this a very simple and easy program but extremely effective,
http://free.antivirus.com/hijackthis/
it's one of the best solutions out there, will literally find almost everything that's hidden and hijacking your PC.
I been using it for years and years, it has never failed me, actually had your exact same issue the other month, thought about reinstalling Windows again but tried HiJack This, it was able to locate the files and fix the problem for me