I am having this problem too. I have gone into Verizon store, called Verizon and called motorola support. They don't have a clue. It does not happen always so I cannot replicate it. My hunch is that it has something to do either with the bluetooth kicking in, or an app getting in the way, or perhaps I am hitting something with my chin while talking on the phone. When it happens and I look at the screen, I do not see the dialing screen that has the mute button or the add call button. Screen is either dark (and I even have to press power button and quickly pull down phone on top left to turn off phone) or I get the full key board and no way to quickly end call.