Multiplayer

So far this is one of the best FPS games that I have bought, Very exciting, Runs great, singleplayer story very nice.
Just one thing, my computer runs this game well, but when I play Multiplayer and get on a server, It seems to give me a
message saying KEY CODE IN USE and I am not able to play any games. I have searched many ways to fix this problem,
but I havent had a way to fix this. Anybody know an answer?

僕はもう何回かFPSは遊んだことがあります。このゲームはとても楽しく、スムーズに動かすことができます。しかし、マルチプレイに
なると、なぜか「キーコード」が今使われており、ゲームを遊ぶことができないと表示します。どうするかがわかりませんので、助けて
もらえますか？

[N!$] Fuku about Call of Duty® 4: Modern Warfare™, v1.7.2