FYI: I was logged in as a local user with a local administrator account. I just did a test installation on a laptop (Windows 10 Home/8 GM RAM) without admin log-in. The result I got on my main machine occurred again. I uninstalled and reinstalled as admin, and the problems were gone. I was logged in again as a local user with a local administrator account. However, a German-language protective program installed on all of our computers called HS Wächter may be causing this, rather than it being a normal problem.
Servus,