Yes, I disabled all user accounts except Dummy1, using Local Groups. And deleted the multi boot entries. I also received the "Welcome to Windows" screen.

Well, my attempt to install 16215 using Kari's workaround instructions was unsuccessful, crashed with INACCESSIBLE BOOT DEVICE after the prolonged, "installing" then booting once and beginning the...

Thank you Kari. I'll be trying this when I have time. I have had failure after failure attempting to install 16215, including from an ISO. BTW, I found multiple *.esd files when I made the ISO. 64...