I've experienced problems with freezing on my Nexus 7 but also apps opening and closing without me touching the screen. It also often flips back and to between an open screen and the history view rapidly. I took it back to the shop who said it was a software issue possibly caused by an app and a factory reset would solve it. I've performed this and reinstalled just a few apps from reputables - sky, Skype, fb etc and the freezing problems are back already. I don't want to have to perform factory reset every time and have to reinstall apps. Its very frustrating. Anyone experienced anything similar?