About 3 weeks ago, shortly after Windows 10 was released, I went thru the Windows 10 upgrade in place procedure on my HP 590t I7 processor desktop machine (which had no problems prior to the upgrade).  About 10 days afterward, I believe following installation of a Microsoft rollup update, each time I chose to "shut down" the PC, it began to shutdown (all power lights would GO off, and all activity cease); and after a few seconds would restart.  I have searched the internet for solutions and have TRIED all that I could find.  For example, I have disabled in BIOS the "wake on LAN" option; I have removed, thoroughly cleaned, and replaced my CMOS battery; I have CHECKED all my Power options and found them to be set correctly.  I have always disabled the sleep and hibernate options on computers I use.  All these actions have been unsuccessful in correcting the problem.  Now, each evening when I shut the computer down until the next day, I'm forced to wait for the computer to shut down, then wait for the inevitable restart, and hold the power button down until the actual shutdown occurs.

If anyone out there has any suggestion(s) as to how I might correct this problem, I would be very happy to receive them.  Of course I can furnish any further details determined to be necessary, but I am convinced the problem has no direct RELATIONSHIP to my individual hardware.This was happening to me, it wasn't the same as a true restart, the PC would shutdown and all fans & disks go silent and then after about 1 second it was as if I had pressed the power button. I can't remember exactly what I did, but I think it was one of these:

(1) Registry:

Location: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon

Double Click on "PowerdownAfterShutdown"

Then,
Change it to "0" if it is "1" OR
Change it to "1" if it is "0".

(2) Device manager:

Network adapter/your network card...
Right click, properties, power management.
If "allow this device to wake up computer from standby mode" is selected. then unselect it.
Salmon Trout:

Thanks for the response.  By the way, your description of the problem you had is a more exact representation of my computer's symptoms than the one I originally furnished.  This morning, I tried both of your suggested corrective actions - but no luck.  Just in case you recall exactly what you did to fix your problem, please let me know.

Thanks again.Just wanted to say thanks because this solved my issue too. My system that I just took the upgrade from Windows 7 to 10 on a Core 2 Duo E4500 2.2Ghz Dell Inspiron S530 at shutdown with Windows 10 would go black screen and act as if it was off yet the system was still in an on state with fans spinning. I thought I was dealing with a power management driver issue. But the registry fix corrected this that you show here. * For the fact that my symptoms are slightly different there might be something more going on here, but this solved it by flipping the value from 0 to 1. It now completely shuts down and doesnt come back to life on its own etc.


Quote

(1) Registry:

Location: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon

Double Click on "PowerdownAfterShutdown"

Then,
Change it to "0" if it is "1" OR
Change it to "1" if it is "0".