Desktop & Screen saver prefs won't load

First follow the instructions in this support article.

If an iPhoto or Aperture library is the source of your desktop pictures, it may need to be rebuilt, or you may need to update the application to the latest version.

Otherwise, continue as below.

Back up all data.

In the Finder, hold down the option key and select

Go ▹ Library

from the menu bar. From the Library folder, delete the following item, if it exists:

Caches/com.apple.systempreferences

and move the following items to the Desktop, if they exist:

Application Support/Dock/desktoppicture.db

Preferences/com.apple.desktop.plist

Launch System Preferences and test. If you still have the issue, put the items you moved to the Desktop back where they came from and post again. Otherwise, delete the items.