Like many, I had problems with screen calibration. Sometimes it just went crazy. I noticed that it seemed to depend on how I hold the phone. I was cradling the phone in the palm of my hand with my fingers / thumb wrapped around both sides. When my fingers are too close to the screen, it seems to confuse the screen calibration. Now I hold the phone with my hand more open and make sure my fingers are away from the edge of the screen. No problems so far.