They crash if they dont have the same musics than a hoster
For example: I have enabled Rayman 1 PSX(Avalible in blockland forums) that is maded by myself at my server
So now, they play it via music brick and CRASHES him and other people too, if they dont have it
Playing it from a vehicle(with stereo mod) wont hurt anyone, but onw be able to hear the musics
So conclusion: Always have same musics than hoster if you dont want to crash
Useful help, no?