I have finally followed the instructions to disable all non-Microsoft services and all startup applications, then restart the PC. It makes no difference. File Explorer still goes back to Desktop by itself. It does not happen immediately and I cannot figure out exactly what triggers it. It goes back usually when I browse photos but I am not 100% sure about this link. The following is just one example of how it happens.
- Open a picture directory.
- Click a photo to view it.
- Click the right arrow or left arrow to move among photos.
- Suddenly File Explorer goes back to Desktop.
Again, I am not 100% sure browsing photos has anything to do with it. It could be a coincidence.
I will enable all the disabled services and apps in an hour or two to resume my work on this PC.