OOC: Habit. Full screen since 1997. The real answer to this problem would be to use the new client and not the classic client.
The new computer can be made to work with classic client if I plug in an external monitor (which I did on Saturday). I get a crick in my neck doing that, 'cause I don't have a good place to put the external monitor.
I've spent some time and energy instead trying to fix my old computer.
At first it would stay on a short period of time then reboot.
I mounted the hard drive into an external enclosure and messed with it using another computer.
After that, the rebooting problem was gone. Unfortunately, it went to a black screen with a mouse pointer on it (even if I wanted to boot to Safe Mode Command Prompt). Ctrl Alt Delete did not do anything, so this was messed up. I could move the mouse, and that was it.
After manually switching the registry files, cleaning out the event log directory, running chkdsk, and setting the file security permissions to Everyone able to do everything, the computer seems to be working again, sort of. I'll consider the problem resolved if I can set the security to something more secure than Everyone Everything. It's probably going to continue to complain about the recycle bin being corrupt, "limited users" not being able to log in, and not be able to make a restore point.
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This has been an adventure. I got to play with Windows 8 and Windows 8.1. These do plenty of things faster and better than previous Windowses, but there are also drawbacks [should be configurable whether you go to Start or Desktop first; Classic Mode is missing, and you can't customize every theme unless you use the registry editor]. I hate the full screen apps thing which might work great on a cellphone screen but is a giant step backward for a personal computer (catch the irony: I play games and do retrocomputing full screen; everything else shouldn't be).