i had the same problem and heres what i did , hope it helps, i was to the point of spiking it off the floor, I never found this solution on line but anywho
hold the on/ off button down for about 30 seconds, it should finaly shut off.
plug it into the computer
delete all the song media what ever ( its what i did)
> how i did that was opening my computer selecting the device and deleteing the contents of each folder
once its cleared of the files re sync your stuff into WAIT until it says someting like you can now disconnect the the device in the sync screen and WELLA my problem was fixed, i'm now happily listening to music typeing this!!!!