Mogul only vibrates randomly

[Spydc]

A few days ago, my gf was telling me that her mogul didn't want to play any sounds and that it only vibrated. I advised her to make sure the speaker was set to on, and she said it was. I had her soft reset the phone and the sound was back on again. A few days later, her phone did the exact same thing while we were together. I checked all the settings on the phone and made sure the sound was set to on, but it would only vibrate. Even when I go to sounds and notifications, it would not play any music.

We did a hard reset and I told her to let me know if it happens again. Well, it just happened again today. Has anyone experienced this problem? She has all the same apps and tweaks I have on my phone:

aim 2.0
google maps
opera mobile beta
codyppc threaded sms
htc streaming media
flash player 7
arcosft mms
and the htc x-button 1.5

She just did another soft reset and the sound is working again. I had her uninstall the x-button app just to see if that is the culprit. I guess i have to contact sprint to exchange the unit now.