Do the following:
Navigate to C:\Windows\System32\AppLocker
Delete the contents of the folder. It will ask for Administrator permission, click yes. If you get an error that you can't delete file(s), you will need to boot into Safe Mode, then it will allow you to delete the files.
So far, even with current updates, everything seems to be back to normal.
Fix posted on Reddit https://www.reddit.com/r/Windows10/comments/9fybz2/shell\_experience\_permission\_error\_fix/
This worked for me. Thank you redditor Hairbear2176
This has been suggested, discussed and tried out several "pages" ago. It works ... for a couple days. Then, back to square one.
Folks! Would be great if you really took the time to upvote this issue in the Feedback App on your Windows PCs. There is really no point in spending time here no more, as Microsoft transfers its support of home users away from here to, first, Feedback App,
then it will be, I presume, by paid subscription only. Given that Microsoft Windows will soon be delivered as a service, home users who don't pay, will now be the 'beta' testers. Merry Christmass!