When I go into a meeting, I pull the notification bar down, and put my phone on vibrate. When I am done, pull the bar down and turn sound back on. Sometimes, not every time, my phone will stay silent. That action permanently deletes all of my sound notification choices. For instance, I go into k9 mail, Facebook, text app, dialer app etc, and there is no notification sound chosen, what so ever, when they all had their own special notification sound before. Anyone experience that? Fix?