Okay cool, that makes sense.
Probably the easiest is to set the filter property for the form in its property box (also set the filteron property to true) and then in the combobox's After_update event, set it again to reflect the selection in the combobox, something like Me.filter = cboStatus (I think that works).
What goes into the filter property is the where clause of a query but without the word where, something like:
status = "open"
Good Luck!