I don't have any start up programs , it's a fresh install. And I do like 100+ fressh install and same thing.
before shut down close any open processes that are not part of windows and try. Also does CTRL+F4 as mentioned work? That also brings up a shut down screen.
Did you install all your drivers ei: Video, sound, network and so on. They all install process that start at startup
Alt + f4 bring up the Shutdown, but I just now installed Windows 8 just to see if this happen with Windows 8.
I didn't, the windows did them all. Then I went ahead and installed the right ones again. It was working fine with build like 10125 and earlier builds. And I'm using UEFI secure boot, not the old legacy one.
New build from MS would be 10142 or 10143. What build leaks (if any), depends on what new build a person can get their hands on.