So, this problem is fairly recent. I have a Lumia 1520, and everything is awesome, but lately, the phone acts up in the way that the 3 buttons get pushed out of a sudden and screen becomes unresponsive, when not even holding the phone. Restarting it helps, but only for a period of time. I noticed if the place where the sensor is, near the earpiece, is clean, it does not act up like this. Phone was dropped once, but the problem did not appear util very later - 1-3 months. I searched the Nokia and Windows bowels for this problem, and i saw that is fairly common. Some say software problems, other say hardware. I used the Nokia Recovery Tool to install and re-install the OS, problem is still there. Would really like the help, its the best phone i ever had, but sometimes i can't even use it AT ALL!!