GE Dishwasher stops at exactly the 72 minute mark every time

My GE dishwasher now stops every cycle at the 72 minute mark. It starts to beep.  I open the door shut it same thing.  No dishes are interfering, no leaks.  I shut off the breaker, turned it back on.  The dishwasher restarts, runs its cycle and stops again at 72 minutes.