I would think the touch screen glass would be the problem. Maybe it's bent a bit, or something. Set the phone down on a sturdy surface and see if it still malfunctions. If so, try to see where it is "taping." If the "taps" are in the same spot everytime while the iPhone is still on a sturdy surface, your problem is the glass itself. Otherwise, if the "taps" are randomly placed, some other hardware is causing this. Hope this helps anyone who has this problem.