This usually is a result of a virus on your computer. The firewall detects the outgoing connection a virus will do to phone home to the creator of the virus. The firewall will close the connection. Try doing a virus scan.
If it is not a virus some firewalls will block high volumes of outgoing traffic because the ISPs don't want you running servers like Bitorrents or Game Servers. If you are doing this then this could be your problem.