[p38fln]

Well, I finally figured out how this is happening - the digitizer is GLUED on to the phone's plastic case. The glue is like rubber cement, not rigid like super glue. Eventually, the glue lets the screen slide into the center of the phone, until the digitizer actually touches the screen - and then, the digitizer stops working.

It's actually very simple to fix - slide a finger nail under the plastic by the speaker and gently pry the digitizer up. Then, put it back. You dont need to remove it totally from the phone. It will flex back to its flat shape as soon as the glue releases. As soon as you stick it back down, the touch screen will work again.