This was referenced in another thread
here and originally found over at XDA regarding issues with the phone popping up warnings that the end-user must adjust their volume using the BT device instead of the phone:
Remove Bluetooth Device Volume Notification
I changed the registry key to remove the erroneous space in it, and cab'ed it up. I also changed the description to "BT Volume Warning" so it is a little more explanatory when you view it in the Sounds & Notifications screen.
Thanks must go to
leanne for the original XDA find.