Originally posted by CyberNomadic
That's a problem with the Desktop settings file, so you have to delete it. First, open Finder, select Go menu (on the menu bar) > Go to Folder, and type ~/Library/Preferences. Then, delete "com.apple.desktop.plist" and "com.apple.systempreferences.plist", and restart. Finally, you should be able to change your wallpaper and keep it