So this is defenitly a hardware issue, received my lumia 930 yesterday and found it not reacting to double tap and going black on placing phone call.. reading through the comment here I decided to realy press hard with my fingers compressing the screen arrea
arround the proximity sensor.. result.. double tapp working and no more black screen when placing call..
So any reset is no solution.... Hardware replacement.. will be a kind of a gamble if I read through the comments.. The phone is perfect.. contemplainting to return it or keep it.. Still it is €400 peice of hardware
I have a new LUMIA 930. I have just started using it and I am having exactly the same problem.
I have no screen protector no case and no dust (unless it was factory applied).
The problem has been in the phone since it was taken out of the box.
The screen goes black immediately I make a call. It makes the handset useless as a phone.
I read your post and on inspection of my phone I noticed that at the top right corner the screen is very slightly elevated. As per your suggestion I applied pressure on this area of the screen and amazingly it had the same result.
The phone has started to operate correctly and the screen stays on during the call.
This is obviously a systematic manufacturing fault, to do with the bonding of the screen onto the hand set.
Really it is wholly unsatisfactory that an issue which is around as long as this has not been dealt with by Microsoft.
I wonder how long this this fix will last for, my fear is that the screen will lift again with use of the phone and the problem will be back.