So I am having this issue that once in a while my nexus 7 won't respond to the power button. Only way to get it to turn back on is to do a hard reboot. Power and both volume keys held down. Seems it happens after graphic intense apps. Games like dead trigger or the transformers movie. Doesn't happen each time I use the apps. Maybe times the last 4 days
I had the same problem too. I think it was Auralux, or something similar (also a game). Are you saying there's a button combination to hard power down the tablet? I managed to make mine come back to life by plugging it in.