I checked "AllowDispaly Fusion to manage the Windows Logon Background" and "Use the current Desktop Wallpaper image for the Windows Logon Background" but that resulted in a solid black background so I unchecked those two options and the Windows Logon background is now stuck at solid black the orignal abstract blue background was not restored.

How do I resolve this problem?

Win 7 x64, I am the admin on the machine.

Open up an elevated Command Prompt.
(Click on Start then type CMD in the searchbox. Right Click on CMD and Run as Admin)
Type sfc /scannow and press Enter.
Take note of the space between the c and the /.
Let the app check and repair your system files.
You may need to reboot but after its finished Log Off and check that all is well.