Hello, a warning to you all: there is a hacker called "Grincher" who has been going around to servers and bricking people's saves. this isn't a joke or a lie. from what I've seen hosts can't ban him. so whatever you do, if you see him LEAVE IMMEDIATELY. It might be a better idea to wait a day or two...
Seems like Grincher can corrupt save data. So, do not open any mail from Grincher, leave any room you see Grincher in, and do not join any room with a 1,000 player limit called "Grincher's Happy Room". This is not a joke.
Edit: Kicking Grincher from your game does not work, they are not affected by the kick action.