Mac version of demo. Launch game. Go to Options. Make a few changes. Try to go back. Instant crash. Every time. (And why do do many developers start their games with music already playing?)
Excuse me, I'm trying to reproduce the bug and I can't. I don't have a Mac to test there, but the bug should appear on Windows as well and it doesn't. Can you give me more details, can you tell me what exactly you do, please? And can you tell me what exactly happens when it crash? Does the screen go black and some kind of error message appear on the screen? Or does the game just freeze suddenly?
Regarding your question related to music, I imagine you're asking this because you were annoyed by the music being loud when you open the game, you went to the options menu to turn it down and that's where the bug occurred. I apologize for that, but I think that opening the game and not finding any music in the main menu, all silence, would be very strange and boring. If you have problems lowering the volume from within the game, I also recommend that you right click on your PC's volume icon, click on "open volume mixer", I don't know what it's called exactly in English, and you can lower the game's volume from there without any problems.