there might also be another problem with the num_clients and the on_server events. I used -diag mode to see the players joining and leaving the server and i once had a diag like this:

Player1 joined
Player2 joined

Player1 left
Player1 left

and num_clients was 1 afterwards although there was no one on the server.
the second "leave"-message seemed to have come from Player2 leaving.
this was still with the same game version as above with dplay_timeout set to 5 seconds