@Owlsroost:
There is one thing, that I have mentioned yesterday:
The volume OSD is only shown, when I'm using the hdmi output of my ATI radeon. When I'm using my realtek onboard soundcard the OSD is not shown.
The volume didn't come back in both cases when I have stopped a ff.
I suspect the volume OSD is shown because the actual audio renderer doesn't support the control interface MP is using for FFWD/RWD volume adjustment (IBasicAudio), so Windows uses the mixer functionallity instead i.e. it's system dependant - but I'm just guessing really.
I'm only planning on trying to fix the actual muting problem, not the OSD display (I can't reproduce the problems anyway, so it would be difficult to work out what's happening with the OSD).