Bought my S4 from BB 6 weeks ago, and now it's having frequent episodes in which the display screen does not respond to any touch inputs. The live wall paper on the home screen is functioning OK, but the rest of the screen is frozen or locked. The fix has been to restart the phone, then the screen responds as it should. So then, I set the phone aside for let's say an hour, then pick up the phone to make a call or open an app, and nothing happens - it looks normal but it's not responding to any touch/swipe kind of inputs. I searched in the settings, but didn't see anything obvious that would cause this problem. Any ideas?