chris r c , your problem had reoccurred many times with other users. It seems that the recent v9.0.50 batches of players seem to work good for a few hours, then decide to die by itself or when you connect it to the computer.
It could be a firmware or hardware problem. i'll suggest that you try flashing all the v9.0.xx series firmwares here
http://www.mympxplayer.org/actions-9...mare-dc37.html
Hopefully one of them gets your player working again.