try downloading malware bytes :
http://malwarebytes.org/
thats probably the best anti-malware program ive come across....

Your best bet would be to install malwarebytes and do the updates, then restart the PC in safe mode (keep pressing F8 as soon as you press the power button the the PC and itll bring up a menu, just use the arrow kepys to highlight safe mode then press enter) and then run malware bytes in there... do the full scan, it will take a couple of hours but finds most things