My wife purchased a two piece snap on hard case with a soft touch finish and now she is having a problem. She came to me and said when she makes a call her screen goes blank and she can't end the call. I tried it out and I got the same results. So I took off the case and the problem went away. So I remembered that there is a sensor that detects your face near the phone and turns off the screen. The hole for the face detector was in the right spot and showing plenty of the sensor. I tried enlarging the sensor hole in the case by drilling to about the max size I could with out interfering with the ear speaker slot and I still had the same results. This was a cheap but quality looking and feeling case we purchased off ebay. So my question is. Do all cases like this cause this problem? Would a slip on jelly like case do the same thing?