Ok so basically every time I start up the game I have to re-input my serial code. Then when I try to join a game it says the code is already in use.

WTH is going on? Is there a fix for this?

same here !

and not only that when ever i try to enter a frigging server it says Serial Code in use or something like that ! WTF !

There's an option, right under "Log In", to save the serial number. Do that.

There's an option, right under "Log In", to save the serial number. Do that.
That option is to save your user name and password, I have it checked off. It does not effect the serial number.

Same EXACT issue here. This svcks.

Smae here I just recieved my copy of pre odered Crysis 2 via steam. Everytime i try and join server it says my code is already in use ???

Please help ?!

I'm having the same problem, every time I start the game the serial is not saved, if I go to play multiplayer and then quit and start again same problem happens.. think I have memorized my key by now.

There's an option, right under "Log In", to save the serial number. Do that.
That option is to save your user name and password, I have it checked off. It does not effect the serial number.

It's literally right under that. I was having the same problem as you and everyone else who's replied with the "serial number already in use" until I entered and saved my serial.

no way.. cd key just won't get saved, if I try to join a server it says the key is in use..

the same her, but i get so upset with that, but i get my copy of the game on dvd version that it says limited edition that have a number to jump to rank 5 and others stuff. i try to play without enter that code. then after that i enter that code on gamesas,.com then try to play multi and my code work and jump to rank 5, then i went to find a server to play, guess what? i was available to play. i dont know what was wrong???????