Firewall blocks "allowed" programs

[DaveFox]

I have a PC running XP media center, and initially was using Webroot's firewall, Microsoft firewall turned off. Periodically, it would block Outlook Express from connecting to my ISP. Webroot's solution was to delete Outlook's access from the firewall permissions list, and then re-allow it. This was only a temporary fix, and the problem re-occurred. I then un-installed the Webroot firewall and installed Zone Alarm, which runs fine on my other PC. Now I have a similar problem, but ZA blocks Internet Explorer. Anybody have any ideas how to fix this?

Thanks.