Battlefield Black Screen!!!

[jojo29]

ok heres my problem. when i play in a LAN game the game always kicks me off and when it does that my entire screen goes black!!!what problem is this???i have the latest drivers on everything i have an ATI 9800pro(256MB) it only happens in a lan game multiplayer is fine and SP is fine also but whenever me and my bro play a 1on1 lan game after about 10-15mins it kicks me to black screen and freezes?!?!?!?!?but it works just fine in internet games and sp mode?!?!?!??!someone please help me??oh yeah and when i reboot my screen drops from its 1024 res setting down to its 640 setting?????