I think just about everyone who designs forms is familiar with that one, but without details, it's hard to say anything substantive. A code snippet would be a good start. Also, the Outlook version and where the form is published.
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Sue Mosher, Outlook MVP
Outlook and Exchange solutions at http://www.slipstick.com
Author of
Microsoft Outlook Programming: Jumpstart
for Administrators, Power Users, and Developers http://www.slipstick.com/books/jumpstart.htm