Preferences app launches fine and all but one prefs pane work well -- the Desktop & Screen Saver preference pane yields the following message:
"Preferences Error. Could not load Desktop & Screen Saver preference pane."
I have tried deleting the com.apple.systempreferences.plist file and re-starting. I have also restored this file from a Time Machine backup. And I repaired permissions. Nothing helped.
Any suggestions appreciated.