After surfing through the links you sent, I called Joy Systems technical support. The attendant connected to my computer remotely, saw the three flags on the Device Manager, went to one of the same Lenovo sites, and downloaded several drivers. Some did nothing, but he eventually cleared all three missing driver flags.
Installing the missing drivers had no effect on the crashing Windows Explorer. I showed him that, and he said it looked like a software problem and showed me a workaround. If I get tired of that; he suggested I run a System Restore on Startup to reinstall Windows. Since that means downloading and installing WELL over 100 Windows Updates, I think I’ll put that off until I have absolutely nothing else to do because the system is otherwise running fine.