I had the same problem with Norton Internet Security 2006 and finally found a solution. I simply right clicked on the Norton icon in the system tray, then under 'options' and 'internet security' and then 'firewall', I removed the ports 20 and 21 from the HTTP port list. This list contains ports that will be blocked, not monitored or allowed. That did it for me. Hope it solves your problem.
-suphu