Hi trent,
I'm not sure how much detail you need, but Kevin's answer is right.
let's cover the bases for hiding a field though;
a) set the "HIDE IF" setting for the dropdown, based on some Session value. for example;
p_web.GetSessionValue('recs') = 0
b) In the date field, add the drop-down to the "reset list" on the "client side" tab
c) In the Validate::Fieldname routine for the date field, calculate the number of records there would be in the dropdown (well, calculate if there are any recs) and set the same session value appropriately. For example
p_web.SetSessionValue('recs',1)
Cheers
Bruce