so sayeth the troubleshooter guide
• When a client task switches out of a multiplayer game for over 30 seconds, the client will lose the connection to the host. If the host task switches out, all clients will temporarily lose connection until the host switches back to the game and the clients may see the network performance icon. If the host does not task switch back before time-out, all clients will drop.

I don't find this to be a feature... instead of ejecting/kicking you from the server you are left with a dead connection and no way to reconnect quickly. Idle timeout is a nice feature but it is annoying with the current state of the mp interface.

Suggestions:
- Add a reconnect button to the "Connection to host lost" Dialog
- Make the idle time a server variable.

Why should you be able to alt-tab out with impunity? IMs, yes. Cheating is another consideration though.

Come on how else are you supposed to pretend to be working?