I had trouble with Norton and the support was a joke. Also found it to be intrusive, as well as hogging resources and huge updates.
Switched to AVG free some years ago. Totally non-intrusive, small updates, never a problem. Also use zone alarm, usefull for telling you about programs trying to access internet, and spybot S & Destroy occasionally to delete spyware.
McAfee give a (free) site advisor for firefox (Much better and safer than IE).
http://www.siteadvisor.com/