If you create a function for the onEndOfMedia field in MediaPlayer, it will frequently, but not always, be called prematurely when starting playback. This is most evident in the case where the end of media handler switches media sources when it's finished playing the current media. The problem is that AbstractPlayerPeer does not check for a valid duration when it tests for a few events.

This was easily reproduced on Mac OS X 10.6, I am not sure if Windows or Linux is affected.