I am writing an application which has a login screen and
a log off button.
When the application loads the login screen is display. The user logs in and a MDI form is shown with various forms positioned within it (thanks megatron for the code to remove MDI resizing).
The user will press a button to log off -- this will trigger all forms to be set to nothing, the mdi form to unload and the logon screen to be shown again.

How do I unload a mdi form from a logoff button without closing the application?