Im running windows 7 and this is what I have done.
Here are the ports you want to make sure are open on your router (TCP & UDP). You might also try forwarding them to your machine.
Listen Port 9378
Beacon Port 7623
Server Beacon Port 6623
Server 5476, 5477, 5478
Game Lobby 9103, 9855, 9856
Also make sure Windows firewall is not blocking Punkbuster (Punkbuster A &
Also make sure the above ports are also open on your local machine. You might try and dissable your antivirus/firewall software and Windows firewall since it defaults when none are present.
Also try DMZ your system through your router. If it works at all after all of that then we know something is blocking it’s communications.
Last resort, reload/re-install!