Buy a PC Mag with an antivirus package (trial or full free) and run the antivirus software on your machine - it should delete the offending virus and allow you to get to tthe Norton site. Or you could visit the AVG site - their antivirus software is still free.
If it's not a virus, then maybe reinstall Windows.
If you really want to be secure replace Windoze with Linux, mind you most of us have too much Windows specific software to be able to do that.