When attempting to open a database object in Design view, or when trying to save design changes to a database object, you ...

When attempting to open a database object in Design view, or when trying to save design changes to a database object, you may encounter this error message.  Access requires an exclusive lock on the database to make design changes on some object types, since other users may attempt to use the objects.  This error indicates that Access has not obtained an exclusive lock on the database. If you change the name of a table, or its field definitions, while someone has the table open, this will result in a serious error for the other user.  Therefore, you must have exclusive access to the database while you attempt to update the object.  When you release your exclusive lock, other users will again be allowed to use the database.