Unable to turn on screen during calls Both of my Galaxy S3s have a problem with their proximity sensors. I make a call, put the phone to my ear, but then if I want to hang up the screen is dead and won't wake up. I cannot disconnect the call until their answering machine hangs up. If they don't have an answering machine, the call just rings and rings until I remove my battery. This is my second S3. Is there a fix for this?
I had exactly the same problem, then set the power button to end calls. But actually if you go to Dialer(keypad), go to Call Settings and untick "Turn off screen during calls". 

It works, as I had this problem since I bought the phone so I think it was set to that as default, because I never even knew how to get in to Call Settings before this problem.