I don't know if this has been solved or not (Much of this thread is in german), but I think I have found a corolation between the server crashing and what happens in MaM.... The server seems to be getting overloaded by RCON commands and then shuts down.
For example; if you send !ban [protected player name] and then it tries to ban them but comes back with "You can't ban a protected player" just as it is executing a banner message the server will crash right there and then. Therefore I think that there is some type of limit on the number of rcon commands you can send to it in a specific amount of time safely without it crashing.
Just an idea,
John