Yesterday i got the same symptom, but my player was paused and nobody touched a button, not on the front nor the remote...
Hijack's Screenblanker was active, when suddenly the unit started switching between aux and mp3.
Remembering this thread, but not exactly, i just pulled the unit out and in again.
After finishing booting, the player was blank again. I tried to press play on the front, but nothing happened. Same on track skip. I opened the menu (all on the front now...) and the item shown was "source". I switched over to info and visual, both were set to off.
I thought, the player had lost the settings, but sound (Loudness and EQ) were still set. I pulled it out again, nothing changed. Went in menu again, down on "source" and selected "player".
Info: Track appeared, showing the pause symbol. Pressed play and it began to play as if nothing had happened...

Seems like quark-impact on the processor... ;-)

cheers