FYI, I tried sfc /scannow
and it came up clean; i.e., Windows Resource Protection did not find any integrity violations.
Regarding restore points, I started System Restore
and checked the list of restore points. There was one for each Window Update and Java Update, and restore points for numerous app Installs and Removals. While I did more installs than appear in the list, I did not reboot after each, so those that appear may have the be last before rebooting.
Therefore, for the time being I'm going to let things remain as they are. Perhaps a future Windows Update will correct the problem. In the meantime I can always 'force' setting a new restore point by installing/removing some trivial app and then rebooting. Not pretty, but....
Thanks for your advice.