Frank,

I've found that causes numerous problems. Modal forms running in top level form do not display, for example, the invalid date message when entered....I believe the message is being displayed in the top level form but is not shown due to the nature of the modal form.
I have base classes in which the top property is set to -21. This effectively hides the windows title bar and makes the window displayed seem as if it is the main window being displayed (i.e. one title bar). This works for any form which will encompass the entire screen and eliminates any problems which might result from using a top level form.

Just a thought,
Brad