i would run hitman pro, malware byes, then avast/avast boot scan. after that you should reinstall avg and the avg extension to your browser. that should clear things up. if it does not there is a chance that your user profile is corrupted as well. try creating a new account, and see if the same problem exists. if it does not move your files over to the new profile and delete the old one.
ART Computer Maintenance and Repair