Can't change lock screen on windows 8.1

I have exactly the same thing happening as you, now.  Screenshot from one of my screens below (this was after 20 minutes of waiting):

I have three annoying problems going on at the same time, all involving icons and images.  I cannot add pictures to the list.  All of them do as above when I try to add them.  If I select the default images already there in the list, I can change it but it only shows in the screen lock preview, and not at all on the screen when locked.  No changes show up when the screen is locked.  All I get is the default blue screen and no images from any account, and I have tried several accounts.

Hi Charles,

There could be possibilities that the operating system files might have got corrupt.

I would suggest you to perform system refresh by following the steps from the link.

How to restore, refresh, or reset your PC

**http://windows.microsoft.com/en-US/windows-8/restore-refresh-reset-pc**

Note: Refer to section: Refresh your PC without affecting your files Note: While performing refresh, the apps that came with your PC or you installed from Windows Store will be reinstalled, but any apps you installed from other websites and DVDs will be removed. Windows puts a list of the removed apps on your desktop after refreshing your PC.

Please let us know if the issue persists. We will be happy to assist you further.

Hi Charles,

There could be possibilities that the operating system files might have got corrupt.

I would suggest you to perform system refresh by following the steps from the link.

How to restore, refresh, or reset your PC

**http://windows.microsoft.com/en-US/windows-8/restore-refresh-reset-pc**

Note: Refer to section: Refresh your PC without affecting your files Note: While performing refresh, the apps that came with your PC or you installed from Windows Store will be reinstalled, but any apps you installed from other websites and DVDs will be removed. Windows puts a list of the removed apps on your desktop after refreshing your PC.

Please let us know if the issue persists. We will be happy to assist you further.

I doubt that there are corrupted files in my case.  I ran chkntfs.  Disk was clean.  I ran chkdsk.  No file system problems found.  I ran sfc /scannow.  No issues or problems reported and no integrity violations found.  This problem simply did not occur until after a couple rounds of updates.  Simply adding the SYSTEM user to the list of permissions made it work again.  This user was missing after the updates, resulting in no one being able to change lock screen settings, not even Administrator!

I am finding that a number of Dell systems are being impacted by this same problem, including my own.  But, unfortunately, I went too far in trying to determine the cause of the issue and screwed up my configuration a bit.  So, there no longer is a list of five previously selected images I can pick from, and previously selected ones will not work unless I rename the image files, but I can at least set the lock screen image, unlike how it was before.

Resetting and Refreshing are out of the question on this system.  They have already been tried and both fail.  There is no restore point I can use, either.  I cleared them all the last time I defragmented my hard drive, which is what I usually do after a large number of updates.  I might be able to use a system image to restore my system, but that would also erase all my other OS partitions because the Windows utility does not have functionality enough to restore just one partition from the system image.  It takes them all out and replaces other OSes with blank partitions after restoring the Windows partition.

The system in question was upgraded from Windows XP to Windows 7 Pro, and from there to Windows 7 Ultimate.  Following that it was upgraded to Windows 8 and then Windows 8.1, but this screen lock settings problem did not occur until after a number of security updates most recently.

What did you need to restore SYSTEM access to?