Lately, when I turn my phone on, it will randomly shut down (to a blank screen) as if it turned off. This can happen right away after the swipe, or sometimes after several screen touches. Always, the phone is back at the swipe screen when I go to turn it on again.
After going thru a restore, I noticed that if my phone remains plugged into it's dock cable, this never happens - I can run the phone without interruption or shut downs.
The battery meter shows full charge currently and it's still happening.