Recently a few users have experienced problems posting to the board, after incorporating Norton Firewall into their environment. Here is a message from one user, who was really helpful, on how to resolve the issue.
Open the Firewall program. Mine has a menu on the left, open Personal Firewall. Next open Internet Zone Control. Click the Add button and make sure the "Individually" radio button is clicked. Next put in the URL www.softwarespecialties.com in the space and click OK. That should do it. I don't see it added to mine so if that doesn't work, let me know, but it looks like the place where I put it. I have two tabs, one says Trusted and one says Restricted. Maybe the sites are there but in a log somewhere, I'm not sure.Let me know if that doesn't work and I'll dig a bit deeper. I don't really care for Norton but it came free with the motherboard so I put it on.
Glad to be of help! 
Figured I would post this, as more and more folks (myself excluded) are getting DSL and Cable, which goes kind of hand in hand with a firewall.