>I am having a problem when I am entering data into a combo box. The data entered into the combo does not get entered into the underlying field unless the data is in the list. I have Style set to 0 - Dropdown Combo because I want the user to be able enter something that is NOT the list. Is there a property setting I am missing to do this?

You should use something like this:
IF combo.displayvalue<>combo.value
*** change source here, e.g.
INSERT into combosource VALUES()
combo.requery
ENDIF