Already tried the ‘Factory Restore of System Only’ but no joy. Ended up buying a WD TV unit and that solved the problem. I’m using the MPW for viewing movies, photos, etc. on my tv and didn’t really like the menu of the MPW anyway (well, couldn’t call it menu really…). So now the MPW is connected to the WD TV box and works like a charm. Haven’t checked yet, if the pie graphic shows up now but I am not really bothered, if it doesn’t.
I had the wrong expectations from the MPW; turned out that it is just an external HD, although wireless. Did spend an additional £60.00 on the box but it was well worth and finally got what I wanted.