fixed - seriously though - for an actual description of the problem - I have only seen this happen to players that at the very least attempt to join a game. This can happen while a player is trying to connect and the host either closes a slot that was open or launches the game with an open slot while a player is trying to join. I have never seen a loss pop up for a player that hasn't even attempted to join a game. It is certainly a bug and something that should be fixed, but I doubt that will happen. Honestly you can't be 100% to avoid this unless you are hosting a game. Your risk is reduced if you normally connect to games VERY quickly, but if you are the type that takes 2-10 seconds to connect - well, this targets you the most. A games host can resolve this by making sure slots are closed and that no one else is showing up in the connect screen before launching.
This started happening on either the last patch or the one before it.
