Scan your System for Spyware/Malware.
http://www.spybot.info/en/index.html
Spybot Search & Destroy 1.6 is a very good, FREE Anti-Spyware Program.
Download, install, update, and immunize your System with it.
Then SCAN with it.
Update it, and scan your System once a fortnight.
http://www.malwarebytes.org/mbam.php
Malwarebytes is as the name says, a Malware Remover!
For the Free version scroll down their page to either download from
Download.com, or Major Geeks.com
Download, install, and update.