More BfME II problems

I have a bunch of computers on a LAN and 5 licensed copies of BfME II. Whenever I try to get into a multiplayer game over the LAN, the game ends for you as soon as any unit from your side dies. It says DEFEATED and kicks you out, leaving your allies high and dry (their end will come soon anyway).

All my machines are running: Windows XP Professional U.S. English 5.1 (build 2600 Service Pack 2) or Windows XP Home Edition U.S. English 5.1 (build 2600 Service Pack 2). I've tried the unpatched game as well as patch version 1.02, 1.06, and the current (1.07 or 1.08). All show the same problem.