Thank you for your enlightening insight. Surely it is silly to use programs which modify Windows appearance settings! Oh wait. This is the Window Blinds forum and changing the way Windows looks is exactly what Stardock does. Bugger off if you're not going to be helpful. The only thing I've changed with Winaero Tweaker is font style and enabled colored title bars.

My antivirus is just Windows Defender. I used Avast! for awhile but had some conflicts with a few games/programs that drove me mad so I uninstalled it. The black screen happens just after the loading animation for the theme ends. I can still see my cursor, and the alt-tab menu, but everything else goes black.

Okay, I may have figured out what was causing it.

I reverted Winaero Tweaker's changes to default and removed it, but it continued to black screen.

Then I remembered my screensaver. About a year ago I managed to get AfterDark 4.0 to run on Windows 10. It runs a little program in the system tray by default, which just opens a defunct options menu. I probably should have thought about disabling it to start with. AfterDark's screensavers seem to work fine without the tray program running, and so far Window Blinds hasn't black screened since I disabled it. I get to keep my flying toasters, and Window Blinds seems to be working fine now. I've swapped themes repeatedly and no black screen.

I'll post again if it resumes black-screening, but I think it's fixed.

The beta version fixed it