Thanks, Derrick, but I've gone through all of those operations and everything is fine as far as services are concerned. I've gone through the Windows Update reset procedures that have been posted in the Microsoft documents, including the manual ones to reset everything and there is no change in this. Something has changed. My machines (all three Windows 11 ones) have all suddenly stopped automatically installing Defender definition updates yesterday and, now, all three of them have a group policy set to not automatically install, but to just notify. I went through all of the group policy options and that one is not present. This is a peer to peer network, not on a domain, and things are going wacky all at once. I may end having to do a clean install of all three machines though I really don't want to. If that's the case, I will have to wait a month or so to get the time to do that.
If you have any more ideas, I'm open. Thanks, again.