This has been an on-going issue for me. When the screen goes dark, at some point after that, sometimes almost immediately, sometimes after several minutes, the music will stop playing. This always happens between songs, never in the middle of one. It is consistant.
The only workaround that I've found is to go into developers mode and set the option to never go to screensaver when the power cord is plugged in.
Does anyone else have this issue and, if so, found another way around it?
Are you streaming? Is it possible that your WiFi is turning off and the playback stops after the buffer is exhausted?