Weirdly enough, I found away:

For windows 7 go to here: C:\Program Files (x86)\Steam\steamapps\common\crysis 2\bin32
Right Click Crysis2.exe
Click on "Run as administer"
Run the game that way and it will work. Trust me, It will, even if u bought it by steam, do it that way.
Oh and if it shows the steam cd key, just click on play cause the game is still running as admin rights

I bought it via steam and I couldnt get it to work. So I pvssyd with EA support and they told me to do it this way. First I thought wtf but after I did it. It worked. I still want dx11 graphics

Why Crytek, Why?

So far I've tried the following suggestions-
Deleting Net Cookies
All caps w/ dashes
no caps w/dashes
All caps NO dashes

AND WHAT WORKED FOR ME???

no caps no dashes!!!!!!!

Try it it MAY work for you!!!

i think i found a fix..... when you log in when you start the game it says you need a key modify that and add your key it working for me so far

Thanks, That worked for me. See ya online!!!

EnlightenedFool... I wasn't suggesting that anyone go and find the keygen (I didn't post the link for a reason). I was just stating why and what I think probably happened... I didn't download an illegit copy of the game... I didn't get the leaked copy, nor a torrent of the day 1 release. I waited patiently for the real release.

And yes, I'd assume using that keygen would be an automatic ban and possibly legal action against you and more if you were to get caught using it. After all, those people that have, are and will use it are the reason that so many keys are being flagged as "in-use", unless (also on the list of possibilities) it's just a glitch server-side that's mis-matching database entries for active serial keys.

But, I still stand by what I said... Since there is a keygen... A new algorithm and new keys is really the ONLY way this snafu is going to get resolved. Thing is, if it's not fixed within the next 24h... 48h tops... I can see a LOT of people demanding refunds for the game.

Further, anyone affected by this issue will want compensation for getting screwed so royally. Money, obviously, is out of the question... But perhaps give everyone that's affected an item that they otherwise wouldn't have obtained until much later in the game. I don't know.. But it's only fair that something be given to them for the inconvenience and broken promises, ya know?

Since mine is (so far) working... I wouldn't have claim to it... Unless, for some reason, it ceased working because some homo happened to generate my key with that keygen and suddenly locked me out of my own game...

Legit customers pay while the pirates play... This is the reason game prices should be 1/4 of what they are now. There'd be less incentive to pirate (because then nearly everyone could afford to buy them). Further, all this DRM crap has just got to stop. DRM has always been a failure and it always will be. It only causes problems for legit customers while the pirates thumb their noses at us and get to play on our purchases.

EnlightenedFool... I wasn't suggesting that anyone go and find the keygen (I didn't post the link for a reason). I was just stating why and what I think probably happened... I didn't download an illegit copy of the game... I didn't get the leaked copy, nor a torrent of the day 1 release. I waited patiently for the real release.

And yes, I'd assume using that keygen would be an automatic ban and possibly legal action against you and more if you were to get caught using it. After all, those people that have, are and will use it are the reason that so many keys are being flagged as "in-use", unless (also on the list of possibilities) it's just a glitch server-side that's mis-matching database entries for active serial keys.

But, I still stand by what I said... Since there is a keygen... A new algorithm and new keys is really the ONLY way this snafu is going to get resolved. Thing is, if it's not fixed within the next 24h... 48h tops... I can see a LOT of people demanding refunds for the game.

Further, anyone affected by this issue will want compensation for getting screwed so royally. Money, obviously, is out of the question... But perhaps give everyone that's affected an item that they otherwise wouldn't have obtained until much later in the game. I don't know.. But it's only fair that something be given to them for the inconvenience and broken promises, ya know?

Since mine is (so far) working... I wouldn't have claim to it... Unless, for some reason, it ceased working because some homo happened to generate my key with that keygen and suddenly locked me out of my own game...

Legit customers pay while the pirates play... This is the reason game prices should be 1/4 of what they are now. There'd be less incentive to pirate (because then nearly everyone could afford to buy them). Further, all this DRM crap has just got to stop. DRM has always been a failure and it always will be. It only causes problems for legit customers while the pirates thumb their noses at us and get to play on our purchases.
Ive really liked your response they make me think instead of just assuming that its been keygend, like everyone else i have the exact same problem and the fact that we can connect to empty servers makes me think it is just a problem with joining populated servers for whatever reason it is should get fixed i mean it is just release day in Aus so not too fussed

G'day from Australia!

Havin the same issue with my key being in use. Redeeming of "limited edition" stuff went fine.

On the + side, So stoked to see a game in which DX11 is well implemented, Unlike that epic fail Dragon Age 2...C2 is runnin sweetly on my GTX 570, i7 2600K.

i dont think this is about pirating. its probably just a simple bug.

Hey guys we have a temporary fix for this error, please check out this thread:
http://www.gamesas.com/forums/viewtopic.php?f=40&t=11741

Hey guys we have a temporary fix for this error, please check out this thread:
http://www.gamesas.com/forums/viewtopic.php?f=40&t=11741

Thanks Tom, But the issue in this thread, Is not the same and therefore, The "fix" to which you have linked, Is not applicable in this situation.

To clarify: When the people who have posted in this thread, Attempt to join a multiplayer server that has players in it i.e. servers that do not list as 0/10 etc, They are presented with a message, Informing them that the serial number they (an individual poster in this thread) inputted, Is already in use.

This is NOT simply an issue of "disappearing" keys.