Noisrev

I have a simple question about the multiplayer map Capture the Island. I've been wondering what was causing the : "Lost!" message to apear and cause the game to end... Back on demo version, I used to be able to play on this map as long as I want without getting such a message. Though now, after buying the game, I cannot play more than a few minutes without the message apearing for a reason which I haven't been able to discover yet... Answers apraciated.