Finally, a solution that works for me as well.
My PC shipped with Windows 7 x64, which I upgraded to Windows 8 Pro x64 practically as soon as it was released. I had issues with 8.0 right from the start. "Modern UI" apps never worked. Ever. I'd heard lots about how upgraded systems had nightmarish issues with both 8.0 and 8.1, but the upgrade went smoothly enough until I rebooted. I was considering simply writing a batch script that'd execute at startup to copy a known good (i.e fixed by SFC) Windows.UI.Immersive.dll into system32 and launch explorer.exe, but never did that, luckily.
So I deleted the WAT folder and the black screen and logoff problems are gone. I can restart without having to fix Windows every single time! Yay! -.- the fact it was ever necessary bothers me. I'm very tech-savvy, but not a MS beta tester, so why should I feel like one?
For what it's worth, the "System" (or "PC Info") part of my Control Panel is now mostly white space, but Windows is indeed activated. I just see the ASUS logo and support numbers. Whatever. Thanks for this fix! :D
Have exactly the same condition here...black screen, after replacing dll file and deleting WAT folder...indeed can login now, and somehow...working, but with a couple anomalies, the "System" (or "PC Info") total white blank, plus cannot go into "Setting", "Action Center" also blank, "User Account" setting not functioning, not sure if there are others...
Couldn't stand this weird condition, got so mad, to the point of formatting and going back to win 8...