I can hide the combobox with it set up as "move and size with cells"
and as long as I choose another checkbox (not the checkbox controlling
the row associated to the combobox) it works just fine. If I choose
the dropdown and select a choice it works fine also. The problem only
arises when I click inside the combobox, leave my focus there, and try
and hide that combobox with a checkbox.

And yes, both the combobox and checkbox are created through the control
toolbox.

Thanks for the response Paul, got any more ideas for me?