My wife's Captivate stopped ringing today... No ringtones, no notifications, no mp3s, no sound on videos...calls show up and you can answer, talk and be heard, just no audio other than that. Media volume up full. Ringer volume up full. Notification volume up full. System volume up full. Not on silent. Not on vibrate. Haven't tried it with a bluetooth headset because she doesn't use one. Hasn't dropped it...nothing like that. Any ideas?