I have this same problem and seems to coincide with version 81 being installed. If you look at the s

I have this same problem and seems to coincide with version 81 being installed. If you look at the screenshot you can see I've set media.hardwaremediakeys.enabled to false and hit volume button on keyboard and the box still pops up. This just started today and I've wasted about an hour at this point trying to resolve this issue. I use my keyboard volume key all the time because nobody's video is set to a standard volume. What did you do to make this obnoxious box start popping up on my screen?