Window 10 is DEAD and how to COLD BOOT !        
Old F8 Safe mode does LIVE !     
But MS killed the F8 key dead today,  how fun is that?  From Windows 95 forward the F8 worked, but not now!

The PC shows windows loading forever is a common symptom.
The dots on screen spin in a tight circle , endlessly?
If the PC HDD and  memory are not bad the below can work and fix this error super easy.
The cure is cold booting the PC, right now it does not, it actually warm boots from a mirror image of last boot.
The PC  boots from a mirror image from hiberfill.sys
(a fast start up feature  gone awry)
HDD/SSD is not dead,
The cure is easy, power on and quickly Hammer the F11 key until you see screen 1 below.  (hit f11 like wood pecker, or as kids say today spam the key (wow))
Then pick See advanced repair options, click that now.
Then piok  startup settings,
Enable Safe mode (means cold boot in our context here)
Press restart on last screen menu below.
If Windows runs ok now, then reboot the PC and all is cured. (easy onces you know the steps)

This is not about black screens of death.
The 3 clicks are here. If the auto recovery screen does not POP, the use the F11 key to get there.

  THIS IS Auto recovery mode.  This menu may auto pop up if the PC fails to boot 3 times in a row.
the goal is get to here, first. CLICK Startup settings.
Line 4 is the new W10 Safe mode. This replaces the old and loved F8 safe mode key.
See the above, now you know  where those geeks at  MS hide your F8 key, it's gone now but moved here. (W10) Enable Safe mode, F8 gone) This also cold boots the PC, and does not use the mirror boot method.
In my case I click safe mode then Restart and WINDOWS now works, I then reboot hard shutdown and  start over and my PC now runs like new, (the SAFE MODE deletes the hiberfill.sys data old )!!!
This mirror file was corrupted, and windows is too lame to notice that, and then ask you, "Dear owner would you like to cold boot now?"  Gee.
The causes are  many, but all causes are bad hardware, or say a gross virus attack.

Nothing beats EXAMPLES:
My PC failed due to my SATA3 (6g) PCI-express card died, (put in new one) and guess what, the hiberfill.sys file is now corrupted. (a W10 feature that, but can be turned off)
OMG, hiberfil.sys is bad now. (it turns out  many things now can corrupt the windows boot files, not just a virus or bad hdd/ssd)

The other bad thing  is in safe mode the Control panel power applet, is dead, when lauched , all advanced modes are grayed out, cute no? (sarc off)
Get that clear,  in Safe mode, I can't turn off, hibernate. Dang ! MS loves to brick wall me here.
 CURE 1:
This is a temporary fix,  we do this fix the PC it runs great then we put it back like W10 had it before:
FIX #1,  In command prompt, you can in fact set legacy F8 back on, using command #1 below.
Cmd.exe (in run box type this) and run as ADMIN (called an Elevated Command prompt or the command  fails)  {It will say successful , if  it was}
  1. bcdedit /set {default} bootmenupolicy legacy
  2. bcdedit /set {default} bootmenupolicy standard
Reboot the PC ,power ON, and quickly hammer the  F8 key, just like you did for since Windows 95,  bingo F8 lives again ! and with it a fresh cold boot and all fresh windows kernal and its drivers. all fresh.
Photo of F8 working after above Red command is issued
No kidding it WORKS !

Once the PC boots and runs ok, you can regress the above steps and all magic image files will be refreshed and clean.
For sure hiberfill.sys  is renewed.

Method 2: (a 2nd way to skin a cat as grandad used to say)
HP year 2006 and newer the F11 key ,takes you to HP recovery mode (hammer the f11 at power button ON)
This only works on REAL HP computers that have not been HDD replace or freshloaded using a MS W10 install full. (I call this a not slammed PC)
Boot to windows 10 install DVD or stick (called install media now)
Then pick
Troubleshoot > Advanced Options > Startup Settings.

Command prompt fixes:

Don't forget command prompt mode above. and the below fixes in hand typed command line key strokes , users commands.

By opening an elevated command prompt (or above recovery page) and typing

Powercfg /hibernate off  (enter key)
These setting ,are global to all accounts.

Disabling "Turn on fast startup" FIXED the problem for me :)
Just go to Control Panel > Power Options > Choose what the power button does and uncheck the "Turn on fast startup".

This forces cold boot on , Fast start is off and hibernate off.)
and no more hiberfill.sys, MIRROR boots and fails. again.

powercfg -a      (full status message , only, and  does nothing to pc,it is a passive query.)
powercfg -h off  (means diable hibernate modes)
powercfg -h  on  (avoid using hibernate)
powercfg /h /type reduced  (reduces the file by half)saving ssd space.

To make W10 more fun (joking)   They moved lots of things out of control panel and in to settings panels. (I click settings, then power)
Click change, first, to ungray the below options.
Then uncheck "Turn on fast startup."  (this makes the boot slower but no more BSOD'S from the corrupted hiberfil.sys file again. ( but to be clear, it was bad hardware that caused this)
See fast startup, turn that off now. (or at least until the PC is healthy again)

Enemy #1 ( If hiberfil.sys  gets corrupted) This is the fastboot file too.  It's a mirror file.    If running in safe mode, turn off fast boot, first. then  you can delete these files.

GROSS hacking ways? (running safe mode fails?)
If in a panic, you can try deleting,  hiberfil.sys,  and let W10 find that and force a DEAD COLD BOOT. (even  a Linux boot DVD/Stick  delete it !)  {not tested by me, this delete action}
In the old days, we could delete all 3 sys files there and the OS would just rebuild them... (The OS sees it missing as the dirty bit, true and does a rebuild) W10 still does !
We  always could  delete 2 files, the hiberfil, and the swap files, in fact we could even turn off swap memory totally , to delete files then put it back later.
Keep in mind all files here are hidden,  so change this, in ControlPanel  +File Explorer optins, + view tab,  windows hides these from you. (turn off hidden files)
All you need to do , is find a way to delete fiberfil.sys, using any methods.
If at wits end, I use a Linux boot disk, and delete the 3 files seen above, or just hiberfil.sys. (this is the mirror warm fast boot file and hibernate file)
If it repeats,  you have bad ram... or a bad driver, or even bad HDD  The HDD is easy to test.

The top causes of the fiberfil.sys file mirror being corrupted  is bad hardware.
RAM or HDD failing. (remove all RAM (DDR2,3,4) from the PC and use only one ram stick to see if this cures corruption.
If you don't like getting a corrupted fiberfil.sys,  then turn off fast boot now.  (or until the true hardware failures are found and cured)

version 1.  10-7-2017