I just bought a copy of Battlefield 2. My brother installed the game on his Windows login account and it worked fine. A couple days later, I tried playing the game while logged into my account, and every time I tried joining a Multiplayer server I got a message saying something along the lines of "Your CD key is invalid." With a bit of research I found out how to change the CD key without re-installing the game, using the support file "Battlefield 2_code.exe" and re-entering the CD key. After doing so, I could successfully join a Multiplayer game online with no CD key problems (it is a valid copy of BF2, it should work). However, after about 45 seconds of perfectly normal online gameplay, the game shuts down, giving me no errors or lag or anything. I did a bit more research, and it seems like this is a fairly common problem. Since the game worked before, I concluded that the problem has nothing to do with my hardware. I am thinking the problem has something to do with the CD key, because the game also works fine when playing Single player. Anyone have a fix? Any help would be appreciated greatly.