I played in multiplayer with my sister in the same room via TCP/IP a while ago and it went wonderful: there weren't problems of any kind. The secret is, IMHO, that both copies of the game have to be IDENTICAL: maybe you have different settings (maybe even a little thing) that could crash the game, so copy you copy of the game and give it to your friend: using the same copy of the game should improve the game experience... Try and let me know