So i have this problem with my cod4 on pc that whenever i try to join a server it tells me my key code is in use. I've bought the game from JB HiFi (Australian retail company). I didnt buy it online or through steam or downloaded a cracked version. I've never been able to play multiplayer and this is also happened to one of my friends. If anybody knows how to fix this or any ideas i would be very appreciative if you shared them. Thank you.