Can anyone tell me why the sound will drop out from time to time on my iPad 2?? Sometimes it can be in the middle of a video and when I press the volume button the volume icon does not appear. A So if I'm in the music app, the volume slider Is greyed out and does not function. It makes no difference if I reset or turn it off and on again but if I just leave it for a while it comes back by itself!!!! Any ideas???? I'm flummoxed!!!