This is a confirmed major bug, but I still can't find the reason.
I have gotten several different reports of auto starting (Disconnecting headset, disconnecting bluetooth, end of a call, etc.), but all of them do not appear when I do it in my office :(
In fact myself sometimes meet the auto-start, but I have totally no idea since I'm not taking log yet. Hope the logged version now will produce more hint.
...First of all, I can only wait it occurs. Grrr.