First i´ll use mozilla firefox blocks so much crap thats trying to capture your pc...
Then antispyware programs...
Also I have found that startup guard is very usefull to get rid of every programs that try to copy itself in a windows startup folder.
Check whats in your windows startup, and you may find very unpleasant programs there...
Here´s link to page which has many and more explains about programs that can be in your startup:
www.sysinfo.org/startuplist.php?filter=