Once or twice a week my 4 year old heavily used 722 refuses to respond to the power button. It's set for it's auto update at 3am. I have changed the update time, sometimes 7am around but that doesn't help. At 6am to 6:30am it just won't respond to the power button (I've changed batteries). I then unplug it from the wall, wait 10-20 seconds and it fires right up. Is this the beginning of a worsening problem?