I got the computer back from the repair shop this afternoon, 100% functional and operational. I had written a nice reply to your post, and then thought I'd reboot it and time the startup to see how long it took so I could add that to the post. It took 29.75 seconds, about what it always did. And guess what? None of the applications would run until I waited 5--10 minutes. Well, not quite. Windows File Explorer ran just fine (nothing else would) and it was NOT a CPU problem, File Explorer would look at all of the hard drives and display their contents practically instantly.

The tech tested it multiple times in the shop, and when I booted it up at home the first time it was perfect. This might be an important clue: when I booted it the first time, the printer was powered off, and the Ethernet cable connecting the router to the computer had become unplugged at the router when I moved the computer hutch to connect the cables to the computer.

After running a lot of diagnostics on the hardware, the tech did what others here suggested: started removing items from the startup menu. However, since his goal was to fix the computer rather than find out the exact cause of the problem, he went through and took out everything in Startup that he didn't think I'd need. That shotgun approach worked, and I have tested almost every single application that I normally use and they all work.

Could my testing those applications have caused the problem to recur?

My Startup menu is pretty simple, although I will have to re-enable the four disabled items outline in red, they are necessary for my Fujitsu scanner to work, I think. (It's the only application I have found that won't work.) For now I'll leave them alone.

I am going to unplug that router cable and turn off the printer power, then try rebooting again, as those are the only two conditions I can think of that were different from the repair shop. I don't really expect this to work. See you in five to ten minutes, I guess...

tanstaafl.