Brainteaser

I have created a form that has two list boxes named
lstYear and lstPeriod. List lstYear is used in lstPeriod
to filter out year specific periods and both provide data
to many hidden text boxes that are used to filter out
information in different queries.

When I have this form in Restored view (not maximized;
just like pop up) and click on lstYear, but not lstPeriod
I can close the form without any error using the Close
button (created with Wizard). However, when the screen
is maximized I get an error. A pop up window "Enter
Parameter Value" shows up asking for lstYear selection.

I can easily resolve this by never using Maximized view,
but would like to solve this if I can.

Any ideas out there?

Thank you.

Lucky