Jeff,
Thanks for the advice. In the meantime I went on to another project, but came back to this one later. I took your advice and imported one clip at a time and tested the commands one at a time. I avoided the “overrides”. It works! Either I had a corrupted original file or selecting the “overrides” then deselecting them caused my DVD to not work the way I wanted. Anyway, all is well.
Thanks
Terry Jordan.