First try cleaning all your temporary internet files and temp files. This is the place where most of viruses and trojens unpack themselfs.
To clean temporary internet files follow below instructions
1) Open Internet Explorer and click on Tools
2) Click on Internet Options
3) On the General Tab, in the middle of the screen, click on Delete Files
4) You may also want to check the box "Delete all offline content"
5) Click on OK and wait for the hourglass icon to stop after it deletes the temporary internet files
6) You can now click on Delete Cookies and click OK to delete cookies that websites have placed on your hard drive
To clean temp files follow below instructions
After cleaning all temp clean up virus and trojans
Try virus scaning of your system with Trend micro Free scanning
Also try rootkit buster
Make sure your system has most updated antivirus. If no antivirus you can also try free antivirus available
Hope this helps