The reason why you're cd key is incorrect is because it has not been entered into the registry. For some reason everytime I installed COD the registry was never updated. If you look under your Activision folder (go to HKey_Local_Machine>>>Software>>>Activision) you'll notice there should be no COD 2 folder at all. The first thing you have to do is give yourself permission to edit this folder. Do this by right clicking the Activision folder then click on "Permissions" in the menu tab. Check to allow both "full control" and "read." Okay, first step done! Now you must create the COD2 folder. Right click the Activision folder and Go to New...and then select Key. Name the folder that is created "Call of Duty 2" In there should be a default key, once you create the folder. Now if you right-click in the larger box you should get a "New..." menu. Click on "string value." Now here are the strings you need to make:
1) name of string value: type: codkey...now right-click "key" and click modify. Now enter your key code in the value data. Enter it w/o any spaces, dashes or periods...just straight type it.
2) name of string value: "InstallPath" then right-click n modify it. In the value data type C:\Program Files\Activision\Call of Duty 2 (or wherever you installed it!)
3) name of string value: "InstallDrive"......value data: D:\
4) name of string value: Language....value data: 1
5) name of string value: StartMenuFolder....value data: Call of Duty 2
6) name of string value: Version....value data: 1.0
And that right there should do it I hope I help some of the ppl that were having trouble like I was. Post back if you want to thank me or if you still are getting the problem. GOOD LUCK OUT THERE!