i was playing my zeki the other day and in the middle of the game, the zeki locked up to the zeki title page. i can't do anything else. if i hold in the "on/off" button, it shuts off, but holding the on/off button in to turn it on comes up to the zeki title page only. i can't navigate to anything else. what's the deal? it's almost like my zeki is locked up. how do you reboot or what's the problem?