This has been driving me crazy.
Mala kept stopping audio on whole computer and tracked it down to this bug. When you hit STOP on an mp3, the fade turns down the wav slider in windows mixer, and obviously this means no more sound for you.
I realised it was probably using the wav slider for the fadeout, so I disabled the fade in/out. But now it just sets it to zero when you hit PLAY on the mp3 instead

So the jukebox isn't usable. Really sucks, spent last few weeks setting everything up and making my own layout gfx etc, and now it looks like going to have to switch to a different front-end and start again.