If you are playing competitive crucible change your settings so only friends can send you messages. There are people going around who will send a message to your fireteam that will crash your PS4. If you get this message leave the group from the PlayStation messages app. If you get stuck reset your PS4 by loading into safe mode and choosing option five to rebuild the database. You can do this by holding the power button for seven seconds. Be careful everyone this is a serious problem.