I've had some success with Norton's automated support.
Go to
http://www.symantec.com/techsupp/support_options.html and click on the "Automated Support Assistant" button. It will ask for permission to install its software so let it. It will then check your Norton stuff and, hopefully, identify the problem and either fix it for you or tell you how to fix it.
It's not 100% effective but it doesn't take very long so it's worth a shot.