I take it this is a software firewall, correct?

If so, I would look in the firewall settings about 'currently blocked' programs and such, and remove it.

If this is a hardware firewall, I would recommend just resetting it.

yeah i agree with stein on that check in your sttings in your firewall but some firewalls are not easy to configure like nortons and maybe it is wise to use a firewall what is easy to use like mcaffees or zonealarm personal firewall as zonealarm is free to download and i must admit that i did used firefox internet explorer but found out that is was spyware as a adaware program i had found spyware on firefox so now im useing explorer 7 and it is fast and makes it alot saver secure than explorer 6 hope this invo helps you out mate take care and all the best and good look with your firewalls :-)