I think this BUG (I am not sure for second part) exists in ALL versions of VFP. It happens when You set ComboBox RowSourceType = 6 (Fields). If you set it to 3 there is no problem with Disapearing of DisplayValue (at least in VFP 8)

Yep. RowSourceType 2-Alias or 6-Fields. It doesn't occur with any of the other RowSOurceTypes.