It is usually when I have played a game for maybe 10 minutes. I don't know if anyone here has played Osmos, but it makes it almost impossible. The game will run smooth as can be, but when I tap the screen, nothing. I will then tap frantically and maybe out of 10 hits I'll get a response from three or so of them. I have to exit the game, restart the device, and start over. It works fine again for a little while.