My Sprint-branded device has the incoming call volume stuck at maximum levels. Pressing the volume keys moves the slider during a call as it should, however the actual volume of the sound coming out of the headset doesn't always change. It seems to work when I make outgoing calls, but incoming calls revert to MAX and sometimes requires holding the phone a few cm away from my head so that it doesn't kill my ear drum. Sound also crackles and peaks because of the volume, making it hard to hear.

I've seen that I'm not alone in this:

But I'm wondering why some people have this problem while others don't. Is there a rhyme or reason to it? Do any VM users get this issue?