Norton Internet security problem

I have had Norton Internet Security for the last year and Norton Antivirus for several years. These are kept up-to-date and have worked real well for me until a few weeks ago. I thought it was a problem with my ISP because I couldn't access Outlook Express or the Internet at all, Kept getting the message "server not found" or "the connection to the server has failed".I finally called tech support at my ISP and he advised me to turn the Norton Internet Security off temporarily and see if I could sign on. It worked fine as long as the NIS was off but as soon as I re-enable the NIS I get booted off.I haven't changed the filtering settings or anything else but it suddenly won't allow any access to the 'net.I'm not very good at tweaking so I usually don't mess with things internally but if anyone has any ideas on this I'd appreciate them. I tried going to the Norton site to the FAQ's but not much luck there. Thanks, MW