When I lock the screen on Windows 8 using 
+ L, the lock screen background image appears, and usually the clock is being displayed, and when you hit a key or Ctrl + Alt + Del, your login and a password prompt is shown.
However, sometimes the clock does not show at all, and pressing keys or Ctrl + Alt + Del will not present anything.
All you see is the Windows lock screen background image, no clock or anything.
I cannot even switch to standby or get the computer to shut down through the power button.
The only way to escape is to force-kill the power by holding the power button and restarting.
However, the mouse is still moving, and Caps Lock still turns the LED on and off.
How can I turn off this security-hardened lock screen that really locks anybody out ?
Has anyone even experienced this ?
Best Answer
This is a problem apparently introduced in Windows 8, and you are far from the only one to suffer from it: googling for this problem got back 220 000 answers!
There are apparently several reasons for it happening and no one really knows why. I list below some workarounds that might work, or not (excepting the one advising disabling the Lock screen completely).
In the article System Freezes on Windows 8 Lock Screen, the following registry hack disables the lock screen image and just shows the password box:
Another advice in the same article was to update the BIOS.
In the article How do I stop windows 8.1 from freezing when the screen locks, disabling sleep has fixed the problem, so perhaps the problem there occurred when Windows went to sleep inside the Lock screen.
In the article Random freeze issue since upgrading to win 8.1, one solution was to turn off Store App automatic update. Another solution was to Use DISM to Fix Component Store Corruption.
I have even found one article where using the mouse wheel fixed the freeze.