Norton Antivirus reacts badly to certain firewalls.
I used to use Norton but had so many problems I not only stopped using it, I completely erased it from my system. NOT ONLY THAT, IT'S NOT A GOOD IDEA TO RUN TWO FIREWALLS AT THE SAME TIME. They have a tendency to fight one another and create unforseen problems.
I now use the following "FREE" programs and no longer have problems:
1) ZoneAlarm Firewall program.
2) AVG7 Antivirus program.
3) Microsoft Antispyware (Beta) program.
The only additional steps I follow is to perodically delete cookies, etc - this cures the two , three, and four times I had to "re" sign into the forum because of my jumping around the forum and generation of messages and postings.
I HOPE THIS HELPS YOU.