Turn off system restore. This WILL DELETE all of your previous restore points, but chances are they are all infected anyways. Then check your dns settings. If your dns servers are getting manually set to some server(s) in a third world country, you cannot trust your web browser results. Fix this by setting dns resolution to automatic or by selecting known good dns servers. Ensure your browser isn't getting directed to a proxy. fix that if needed. Then get and run combofix. Follow the instructions carefully. http://www.combofix.org

After, and if, combofix is successful, re-install your AV software (a good one with updated AV signature DB) and run a full scan.