|Google, download, update and run the following:|
Spybot search and destroy
The above are free
If you do not have an Anti Virus i would recommend you get AVG
if you do not have a Firewall i would recommend ZoneAlarm
Both available Free and Paid versions
before you scan, make sure you update each software, once you have updated them, restart the machine and enter safe mode. Run each software let them all complete, remove any threats detected.