Senna,

You must issue a NODEFAULT to stop VFP from processing the keystroke. You won't need the SetFocus call with a NODEFAULT.

WITH THISFORM
   DO CASE
      CASE nKeyCode=24  &&&& Down Arrow
         IF .List1.ListIndex <> .List1.ListCount
            .List1.ListIndexX = .List1.ListIndex + 1
         ENDIF		
         NODEFAULT
     CASE nKeyCode=5  &&&& Up Arrow
        IF .List1.ListIndex <> 1 AND .List1.ListCount > 1
           .List1.ListIndex = .List1.ListIndex - 1
        ENDIF		
        NODEFAULT
   ENDCASE	
ENDWITH