Hi Steven,
thanks, that version works. Interestingly, after it finally started up, it asked me whether I wanted to move my music library from my E to my D drive. That change of Drive Letter happend when I reinstalled my PC a couple of days ago. So my current guess is that MusicBee found files of the previous installation somewhere on my PC and tried to use that. Perhaps the portable version doesn't do that and that is why the portable one works?