If you have sound turned off in PSlaunch the game will crash randomly for you. As I assume there is a good reason for you to have sound turned off and suggesting to simply turn it on again is no solution here is another workaround:
Go to your PS configuration directory (linux: "~/.PlaneShift", MacOSX: "~/Library/Application Support/PlaneShift", Windows: "%AppData%\PlaneShift") and find the "planeshift.cfg" file. Open it with your preferred text editor:
vim ~/.PlaneShift/planeshift.cfg
Now add a "System.Plugins.iSoundManager = crystalspace.planeshift.sound.dummy" line at the end (Without the quotes of course. Maybe check if there is already a line starting with "System.Plugins.iSoundManager" in the file. In that case remove that old line first). This will make PS uses a dummy soundmanager...in the end more or less the same as disabling the sound. Afterwards the crashes should stop (And you can listen to other playing their new instruments or enter ojaveda).
Edit: Yes...even mac users have the right to have their OS spelled correctly