That’s amusing, I just logged in to report this bug… and here it is already.
A few additions
First off, this is 100% reproducible on my Empeg. Set up the display to blank or power down, and ~36 minutes later it stops playing. The display goes off in the requested time (currently 45 sec) @ 65% screen, and gives no indication of any problems. Then later it just powers down. Hitting the down button will wake it back up, and it starts playing just where it left off. This occurs running on AC power, I have not tested it in my car.

Let me know if I can provide some more useful info.

(edit) - forgot to mention that this is NOT new, and is at least 4 Hijack versions old.