Came across this problem yesterday, after restoring my Time Machine into a new Mac running Mountain Lion.
Basically, no matter how I try removing or adding any Wallpapers Folder into the list on the left, opening this "Desktop & Screen Saver" Preference Pane again will just reset everything.
There are apparently people having the same problem, but after trying all of the suggestions, none works for me:
https://discussions.apple.com/thread/4940397
https://discussions.apple.com/thread/4793021
Anyway, here's how to fix it:
Open your terminal and type in:
That will move exactly the below two files:
Basically, no matter how I try removing or adding any Wallpapers Folder into the list on the left, opening this "Desktop & Screen Saver" Preference Pane again will just reset everything.
There are apparently people having the same problem, but after trying all of the suggestions, none works for me:
https://discussions.apple.com/thread/4940397
https://discussions.apple.com/thread/4793021
Anyway, here's how to fix it:
Open your terminal and type in:
$ cd ~/Library/Preferences
$ mv com.apple.desktop.plist* ~/Desktop/
That will move exactly the below two files:
$ ls ~/Desktop/
com.apple.desktop.plist com.apple.desktop.plist.lockfile
Restart your mac and try adding / removing your Wallpaper Folder in / out again.
After confirming that everything is working, move those two files into your trash.
After confirming that everything is working, move those two files into your trash.