I have Norton Internet Security 2011 installed for aboutr 4 months now and for the last 3 weeks or so, I have been having the Internet connection turned off by Norton. I try to research the reason and can only find out that Norton Intrusion Prevention is causing if, but I can't find a cause other than that. I can disable Intrusion Prevention for 15 minutes and restart and usually get it back. Most of the time when I look at 'History' I don't see and entry explaining it but one time I did and it seemed to indicate that my 2wire modem was the cause. At least that was the IP address that I saw.
I have been having a problem even longer with establishing an Internet connection on startup. I can't connect and when I look at 'Network and Sharing Center' in the Control Panel, there is a red X on the line between Network ------- Internet. I am running Windows 7 Home Professional and my connection is Ethernet wired to the 2Wire. After I wait about 15 minutes the red X disappears and I can connect. I somehow think this might be connected with my Norton product. Does this ring any bells?