There is some new information regarding the multiplayer problems, posted by Crytek’s Community Manager Alex Werner.
Greetings Community!
We just would like to let you know that we are aware of the currently occurring issues regarding playing Crysis Multiplayer online. We are already in touch with Gamespy, EA and the world-wide server provider to resolve the problems. This topic has the highest priority for us now and we hope to come up with a solution as quickly as possible.
What we figured out so far already is that when you uninstall the MP Beta/SP Demo after you have installed the full version of Crysis your CD-Key might get removed accidentally. If this is the case please have a look at the workaround we provide further below. There is no guarantee that these work, but they have been helpful to many out there already.> Mainly all he suggested is already tested with negative result. One solution is not tested though :
Add CD-Key manually to Registry
1. Windows XP: Start -> Run
2. Windows Vista: Start -> All Programs -> Accessoires -> run
3. Type in "regedit" (without "") and press Enter
4. Windows 32-Bit: Go to HKEY_LOCAL_MACHINE\SOFTWARE\Electronic Arts\Electronic Arts\Crysis\ergc
5. Windows 64-Bit: Go to
HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Electronic
Arts\Electronic Arts\Crysis\ergc
6. Check if your CD-Key is available as value in the right window. If not
double-click on "(Default)" and type in the key without "-" and in capital letters.
TESTED : MY KEY IS THERE. NO CURE THEN :(
Source : InCrysis