There is a portion of my iphone screen that doesn't respond to touch. it's about 1/2" high and runs straight across the screen. on the main screen, i can't hit the buttons for clock, calculator, notes or settings. for text messages, i can't hit the send button. on the phone keypad i can't hit the 7, 8, or 9 keys. I've tried rebooting and also resetting the phone in itunes. No luck. Has anyone else had this problem?