Same thing happened to me, I just disconnected my zune from my 360 after charging it and then I was about to play a song and the screen froze and went in to sleep mode, I can still see the song I selected (dimly lit on sleep mode) and it won't connect to my computer or 360 anymore
my zune did this too I unplugged my zune 8gb from my 360 and it went to black and wont turn on or reset or anything and ive plugged it in to my cumputer and ewverything
You rock i heal up in the center circle and the back button and my 80gb zune came back on after stoping and going black. I was scared it was trashed thanks