Use your anti-spyware/malware and virus programs and make sure that your system is clean....
some free ones are :

spywareblaster
SpywareBlaster Download

spybot S & D
The home of Spybot-S&D!

Ccleaner
CCleaner - Downloading Slim...

ATFcleaner
ATF-Cleaner download and review - clean browser tracks and temp files from SnapFiles

avira personal
Avira AntiVir Personal - FREE Antivirus

Clean your computer and if you still have any issues post back again and we will go from there