Do you need to unload the form or just hide it when the second screen appears?

If you just want to hide it, just befor calling your second screen do THISFORM.Visible = .F. this will temporarly hide your screen until you do
THISFORM.Visible = .T.

it should look something like this

THISFORM.Visible = .F.
DO FORM YourFormName
THISFORM.Visible = .T.