How do I handle explorer.exe class not registered?

I've got Windows profiles set up on my PC for members of my family to use. They log into their Microsoft account into their own profile. My daughter has been having a lot of problems running almost all programs she's got on her taskbar. For example, clicking on the File Explorer button on the task bar brings up a window that says: explorer.exe in the window's caption simply the words, "Call not registered" in the main content of the window. But it certainly does NOT bring up File Explorer.

What makes matters worse is the search button on the taskbar is completely useless. It doesn't do anything and she cannot type anything into it.

Pressing the Windows button on the taskbar is also useless.

I've searched the Internet trying to find how to fix this. I'm seeing answer that go all over the place. Everything from uninstalling the last Windows update, to a slew of things to do, one after the other. Here's a sample:

Class not registered on Windows 10 [Solved] - Driver Easy

I would like to know and I'm hoping someone from Microsoft is monitoring this forum, how do I fix this problem?