The closest i've come to finding a pattern to the behavior is that it tends to occur if I do a lot of rating/tagging ie play song for few secs, change the rating, then play next song.
Anyone else ever notice this?

Edit:
I'm running Vista Ultimate and this has happened with all 3 alpha builds.
I also noticed something similiar occuring with the MM2 player back on XP. The song name would stop scrolling and the player controls would become unresponsive, but the skinning never completely disappeared like this. Also it occassionally would automatically resolve itself with MM2. Currently on MM3 I have to exit MM before the skinning returns. Closing it to the system tray doesn't help.