Here is another gamestate error and I know who did it. It was Kiranfoxdemon. For those that don't know yes it is forced and the way you do it is by using a program. I can't remember what it is called unfortunately but did hear people talking about it one day, basically what you do is while you are in the game you alt tab get into the program and then change values such as health,money, etc.. to values that are impossible like a million, this causes a gamestate error and ends the game.
The Easiest way to catch them is watch the replay (it will be called last game) go to where to problem occurs, look for the enemy teammate that is NOT MOVING, this means he has alt tabbed and is running the program.
Here is my replay where it just happened.