I play wolfenstein enemy territory at FUN server, mi nickname es Lollipop, I'm friend of Croma and he is upset because a member call Kriss stoled his nicknmae "croma***" and put it as his profile on, what to do in that case?

If you go to the user's GameTracker profile, you'll see a little REPORT button next to the nickname he/she is using. You can hit that and send a little message so we can take care of it.