Select Case Me.YourCombo
Case "TextA"
Me.Field1.Enabled = False
Me.Field2.Enabled = False
Me.Field3.Enabled = True
Me.Field4.Enabled = True
Case "TextB"
Me.Field1.Enabled = True
Me.Field2.Enabled = True
Me.Field3.Enabled = False
Me.Field4.Enabled = False
End Select