Since I installed iOS7 beta 2 version, my touch screen started to go unresponsive from time to time. After a couple hours of internet research this is what I found:
iPhone unresponsiveness is mainly caused by notification messages being sent behind the lock screen. For example, when your battery reaches 20% you get a notification on your screen. There is a bug that may send those messages behind the lock screen giving you as a result an unresponsive screen – your iPhone is waiting for a response, but since you do not see the window because it is behind the lock screen, then you cannot respond… and well, you know.