I believe that on Macs (and probably other Unix-based systems) that when you logoff (or otherwise disconnect from the leaderboards, even), you somehow call a function that crashes the game. Upon leaving the LBs, you have about 1-2 seconds after seeing the home menu to quit, or else it will lock up and you must terminate it. If you look in the activity monitor and check the open files for MarbleBlast, at the bottom of the list you will see that a music file (Pianoforte.ogg?) is open. But if you look at the list and disconnect, the game suddenly closes the file. If you exit immediately (and sometimes if you just wait), it will spawn this message in the log near the end: "File IO error: Bad file descriptor". If you quickly exit, it will appear in the OpenALShutdown() function. Othertimes (if you wait and it crashes), it _may_ appear in the log, but before that function. Maybe the main menu is calling the closed file, and that causes the error (before the OpenAL shutdown sequence can close the file).