The Undo list is cleared when you click "Enable Content" in Access 2007

When you click Enable Content for a database in Microsoft Office Access 2007, the Undo list is cleared. Therefore, you cannot undo any major changes that you made to the database before you clicked Enable Content. These major changes include deleting a table or a form from the database.

When you click Enable Content for a database, Access 2007 saves, closes, and then reopens the database. These actions clear the list of the most recent actions that you can undo in the Undo list on the Quick Access Toolbar.

Typically, databases are restricted in their functionality when they are opened. If you create or modify a database, you must enable that database. Because the Undo list will be cleared when you enable the database, you should enable the database as the very first thing that you do when you create or modify a database.