What you mean by code in use?

It's probably the downloaded version then
you could try to get a new key or just buy a new key
or if you bought the game then you could try to contact the game makers (their email adress is probably somewhere on their website) and explain your situation and attach a proof that you bought the game have the key blocked and receive a new one

Please help me...HOW TO FIX THE PROBLEM...PLEASE
i cant play any server
i try to play with another profile...but "key code in use- Please Try Again Later"

It's rubbish, sure i downloaded the game ^^ but i can't be that every cd-key i tried was used at that time. I tried like a hunderd and still it said CD-Key in use.

Where can you buy an online key for this game?

Just says key code in use when I try to play online... is there any place I can buy a key code online?

I used CD KEYs DIRECT once, but there are others you can buy an online key from. There is an issue with COD4 not disconnecting your CD Key properly regardless of whether your game crashed etc. Simply logging out normally from the game will cause the 'CD Key In Use' error. I have two computers with COD4. One has original sealed retail install with it's original key and the other PC has an intallation from the retail CD, but with the key I purchased online. Both have Keys worked at the same time as well as individually, but both get the same error frequently. Rebooting your modem will cause the master server to drop your CD Key from use 90% of the time from others and my own experience.

It is NOT an issue of your 'CD Key In Use', a duplicate key or otherwise (unless your friend borrowed your game maybe.) It IS an issue with the master servers registering your key as still logged in. Thus far the issue has not been rectified and appears to be quite random amongst the Battlefield and COD4 community and who knows who else...

Game support these days is lacking and now it's all about massive shipments and uploads for sales even though games clearly were not ready for retail market with some having more than a fair amount of bugs in them. A games shelf life and it's continued issues would not be something support wishes to dedicate too much time once sales decrease and the money made, so consumers have to lump it. This issue here is getting old.

Hope this helped.

On the Activision website however, they tend to point at everyone's modem as being at fault. I have a 'natural' firewall. Have been able to play online many times without touching anything. Activision recommends port forwarding, but that forces me to turn on my higher levels of firewall in my modem and port forward every single thing I use through it. I have had reports of people having success in port forwarding COD4 and it's fixing the 'CD Key In Use' issue. My information is based on what I can gather and others opinions as well. If your interested here is the link:- ivision.cfg/php/enduser/std_adp.php?p_faqid=19511&p_created=1194554858&p_sid=UMyDVABj&p_accessibility=0&p_redirect=&p_lva=&p_sp=cF9zcmNoPTEmcF9zb3J0X2J5PSZwX2dyaWRzb3J0PSZwX3Jvd19jbnQ9OTQsOTQmcF9wcm9kcz0xJnBfY2F0cz0mcF9wdj0xLjEmcF9jdj0mcF9zZWFyY2hfdHlwZT1hbnN3ZXJzLnNlYXJjaF9ubCZwX3BhZ2U9MSZwX3NlYXJjaF90ZXh0PW1vZGVybiB3YXJmYXJl&p_li=&p_topview=1

lol some of you guys don't know crap, and your spelling sucks too.
so first, if you found the cd-key in the internet, u have to be so freaking lucky if you can play with it, because it is trying to be used by thousands on the internet.
second, if you bought it from amazon, you have to ask the dude which sold u the game, because he is playing it with, now, your cd-key.
and it doesn't matter if you downloaded the game or not, you just need a valid or unused cd-key...
and you can change the cd-key in multiplayer options somewhere, i haven't played cod 2 or 4 for ages...
what frag said i don't know exactly but i have done it my way often and my experience is that it was used by an other player or pc that was using the same key

Hey i just wanted to ask if i buy a cod 6 original can i install it on 2 different pc and use the same code of steam on both and play it on both pcs ?

Someone have your serial