[yldstrk]

My computer has been unmuting at will too, kind of mysterious

[Steely Tom]

My computer has been unmuting at will too, kind of mysterious

Here is a solution:

1. Right-click on your volume control (the little speaker icon on your taskbar). A "pop-up menu" will appear.
2. Click the "Playback devices" item on this pop-up menu.(here "click" means "left-click").
3. Find the playback device you're using (in my case it was "Headphones").
4. Left-click on the device you're using. Another pop-up menu will appear; on this one, select "Properties." A "properties" dialog box for your audio playback device will appear.
5. Select the "Advanced" tab in that dialog box.
6. You will (or should) see a checkbox labeled Allow applications to take exclusive control of this device. Un-check this check box.

That solved the problem for me.