Does anyone have the problem? The Nexus 7 goes to sleep, I press the on button then sweep to get in. The screen then goes blank. You press the On button and the sign in screen appears again. Sweep & blank screen comes up. It seems as if it goes to sleep again. To get back in I need to power the tablet off and then on again. I think the problem may have something to do with the speed that I sweep to get in.