Thanks to hints in the previous posts, I found the "cause" of my volume slider automatically dropping to zero. I have a gateway FX-173 portable with an attached monitor and microsoft radio mouse and keyboard. The big hint in previous posts was keyboard
and mouse problems along with the volume slider problem. Indeed, I noticed that when the volume slider was doing its go-to-zero thing, the mouse action was erratic in several programs, including selecting items in Quicken pull-down windows and selecting text
in Internet Explorer. So like other posters here, I started fooling around with the portable's native keyboard and touchpad, the attached keyboard and mouse, and .... I discovered that when I moved the Gateway portable's lid toward the closed position, the
volume slider starting going to zero!! And, when I opened the lid, the volume slider stopped!! The lid does not have to be completely closed to start the volume slider moving. So while I don't know the root cause, I suspect it is in the power options for
behavior when the lid is closed.
I doubt this fix will work for everyone, and I cannot yet point to a root cause. But adding my experience to the others in this thread, I suggest that you look closely at any add-on keyboards and mice, and the position of your laptop lids.
I'm going to poke around in Power Settings to see if I can find a lid close option choice that fixes the issue.
Meanwhile, good luck to others that have a variant of this volume slider issue that doesn't yet have a solution. This issue really deserves some serious attention by Microsoft to discover a root cause and fix it for everyone.