Please follow all the directions found here. After you get to step 5, if your problem is not resolved, post a HijackThis log in the Malware forum. If your problem persists after getting a clean bill of health from a malware expert, return here and we'll continue troubleshooting.
Keep in mind, the malware forum is very busy and can take up to 5 days to receive a reply. There is a special forum called The Waiting Room if you've been waiting for 3 or more days. You can put a link to your topic & a short description of your problem and someone will get with you soon.