After I complete a call my screen goes dark before I can exit the call. So I have a black screen and still connected to the caller without any way to exit. After pushing the on-off and waving phone I can get the screen back. Very frustrating. This did not happen until a couple of months ago, about 2 months after getting phone. I know phone is suppose to go dark when held to ear to avoid pressing other buttons but this is after that and holding phone both horizontally and vertically. Ideas? Thanks,