Screen Background Reverts to Default Black

I've had this problem for a couple of months now, and unfortunately can't remember exactly when or under what circumstances it started. After setting my laptop screen background to the "Cool Blue" color and going about my business, the color seems to arbitrarily and randomly suddenly revert to the default Black color. I then have to go into Settings and reset it. Sometimes, when it seems to be starting to happen (a couple icons or one of my Fences changes) I seem to be able to head it off by doing a "Refresh" - but only SOMEtimes.

I did try to figure out the problem by searching on the Internet with no success. Although... I do remember something being said about it having to do with one setting the screen icons to disappear and/or appear. I'm not sure if this was really the cause or just speculation. However, I immediately thought of the Fences (which I use and love) function of the "double-click" to make the Fences and icons stop showing. Perhaps they are related?

Any ideas here?