Can't perform operation because the project is protected

When a project is protected, certain actions are prohibited. This error has the following cause and solution:

• The project was inadvertently protected.

  Remove the protection, and then try the action again.

• The project was intentionally protected.

  Don't attempt the action until the protection is removed by the person that applied it in the first place.

For additional information, select the item in question and press F1 (in Windows) or HELP (on the Macintosh).