Multiplayer with cracked game

Hey !
I downloaded COD5 yesterday, Solo works (with a crack) but i can't play online.
I used a serial found on internet.

I tried to create a profile with a soft it works but 5s after lauching the game : Crash and "Unhandled exception caught"

Do you know how to do ?
Thanks


And sorry for bad english, I come from france

Hmmm then download call of duty multyplayer from the internet