Symptom
System Preference panes such as Energy Saver or Date & Time appear with the locked icon and do not accepts changes, even from an Admin user. Clicking on the lock button does not open an authentication dialog as expected.
Solution
Quit and reopen the System Preferences application. Be sure that you are actually quitting the application, and not just closing the window.
Follow these steps:
1. Click the System Preferences icon in the dock.
2. Choose System Preferences > Quit System Preferences (or simply press Command-Q).
3. Reopen System Preferences by choosing Apple menu > System Preferences.