Fixed it! Thanks. I had already spent hours tracking this down today. I really appreciate your help.
This is what causes my problem: I copy and rename whole project directories and then import the "new" project into the workspace. I have learned to update several parameters when I do this, so I guess I have a new one to add to the list.
You have a fantastic blog -thanks for sharing, it has saved me hours of work again.
Thanks again.
Ian