Data is saved in a table, but the table layout is not saved due to design.

Cause:

Data entered in a table in Datasheet view is automatically saved, but design or layout changes made in Design view are not. This is by design of Access 7.0.
NOTE: Access DOES display a prompt before exiting a table, asking whether to save design changes.

Solution:

When changing a table's design or layout, save periodically and save before closing. To save the table's design or layout, select the 'File' menu and select 'Save'.
NOTE: When closing the Table Design view without saving, Access displays a prompt asking whether to save design changes.