halo multiplayer

[Fuken_Smartazz]

just to start off, this is not a warez question, my problem is not with a warez or hacked version of the game. myself and two of my friends have tried to play halo online. we can only get two of us actually in the game. i host, one friend can get in then the other gets an invalid cd key error. if the second friend gets in first then when the first friend tries to join he gets the invalid cd key error. the same also happens no matter who hosts the game. no matter what we do we can only play two at a time, whoever the third person is trying to join they get an invalid cd key error. and before anyone responds with a samrt comment about buying the game or anything near that, we all three have our own legal retail copy of the game purchased at different retailers. i have spoken numerous times with microsoft tech support and have found no solution. i have tried uninstalling the game, removing all registry entries for the game, reinstalling it in a different directory, updating, tried running the game on gamespy instead of a direct ip connect and still no results. has anyone had a similar problem with this and if so how did you correct it. i dont understand the invalid cd key error as we all have legal copies of the game with our own cd key. we ar not using the same cd keys or hacked versions of the game, we are 100% legal and legit here. any help would be greatly appreciated. thank you.