Hi. Nice of you to inquire. Are you having similar issue? While it happened 2-3 times early on when I first acquired my D800, I've now used it a fair bit (some 20-30 hockey games, pro/AHL and amateur)and it has not reoccurred. I'm hoping the issue actually was with the user (me!) and not the camera. I suspect it may be that the battery was so low it was not turning the screen on when asked, nor allowing any of the back side buttons to function. I've also acquired the grip and second battery...so I now never really run on low power....that's why I suspect low power main have actually been the issue (or should I say clueless user was the issue.) I'll post again if the issue arises again.