And the problem was....?
The problem was (
is) the HHD in the Mac mini. Being cheap, i bought the base model with a mechanical drive. TechToolPro started giving me S.M.A.R.T. warnings but can't, of course, fix it. At least it is still covered by AppleCare, so it goes to the only Apple Authorized Service in town for further testing and hopefully replacement. I'm literally limping* through the weekend until the appointment Monday.
Actually, I'm limping because I broke loose a bone spur on my big toe! Wearing a hard sole boot for a couple of days. Allowing me to postpone several 'honey-dooos'! I'm thinking I might be able to run the vaccuum by the end of the month... maybe.