Windows 10: Periodically there is no login prompt on login screen; can't verify

I have a vexing problem since the Anniversary update on my Vaio. I have been using Windows 10 on this machine successfully for over a year. Here are the exact symptoms:

• I boot up the laptop from a cold state.
• The boot appears normal and my personal background appears on the welcome screen with the current time and date. Normally, I would just need to click anywhere on this screen to receive my personal photo and a login prompt. Up to this point, by the way, I have not heard the Windows dah-dah-di-dah-hmmmm sound.
• When I click on the welcome screen, the background stays, but seems to zoom in slightly. No personal picture appears, no login prompt appears. The only icons are the WiFi icon and the accommodations icon for visually impaired. Both of these icons function normally, but nothing else does, not ctrl-alt-delete. Not the enter key. Nothing.
• Eventually, after about a minute, the welcome screen with the date and time returns, but clicking produces the same result as before.
• I am forced to hold down the power key until the computer shuts down and then press it again to boot.
• At this point, the process usually proceeds normally (with the dah-dah-di-dah-hmmmm sound) and the login screen with my (circular) photo appears and the login proceeds normally.
• Other strangeness: I am unable to verify my identity on the computer because clicking on Verify produces a Windows security error: We couldn't sign you in."
• I tried resetting the Windows explorer advanced internet options, and it didn't help.
• I added SSL 3.0 to the checked internet options, and it didn't help.

I am afraid that all of these forced shut-downs will eventually degrade the performance of my computer. Help!!

:)

 

No Login Prompt on Home Screen

I can't even start in safe mode. The screen is black. When I try to do a startup repair, an admin password is required. My admin tried every password they have ever used and it will not let them in. When you go to security, it says that the admin password
is not set. I have been locked out of my computer for two months and there is nothing I have read that will help.

This is very frustrating since it is a Microsoft issue and there seems to be no fix.

 

No Login Prompt on Home Screen

Power on and off your computer three times

On the third time, your computer will boot into the Advanced Recovery environment

Click Advanced Options

Click Troubleshoot

Click Advanced Options

Click Startup Settings

Click Restart

Press (4) to Enable Safe Mode

Wait while Windows 10 starts in safe mode.

Log in

Press Windows key + X

Click Device Manager

Expand Display Adapter

Right click your Display adapter and click Uninstall

Exit Device Manager

If you have an older Antivirus utility also uninstall it.

Restart

 

Additional information: I tried to solve the forced shutdown issue by changing the function of the power button from sleep to shut down. However, this type of shutdown brings the problem right back. I have to hold the power button to completely turn off the computer, then the next boot produces the windows sound and the login screen appears normally. Also, I solved the verification issue by creating another administrator on the computer and was able to verify my identity using the new user.

 

Solved: When I realized that there was a difference between the forced shutdown and the normal shutdown, I thought maybe those crafty Windows programmers figured out a way to keep Windows partially awake in order to start up faster. But in my case, that was causing my boot up process to partially fail. Soooo I turned off Fast Startup and sure enough, it has solved the problem!! Here is the procedure:
How do I enable or disable fast startup?

• Type Control Panel in the search box.
• Click Control Panel.
• Click Power Options.
• Click Choose what the power buttons do.
• Click Change settings that are currently unavailable.
• Scroll down to Shutdown settings and uncheck Turn on fast startup.
• Click Save changes.