If you have FTP access to the server. Check a look at either games_mp.log or console_mp.log and try to find a section in the log where many people have disconnected all at once. Look for a keyword that says the they disconnected. I'm not sure what the force quitting the server command is, but it's usually DISCONNECT_EXE or something like that. Also, when the server does crash, the error that usually appears is " "game_name" attempted to overload var()", so that could be a keyword as well.