BTW - fixed it.. The problem was the nut behind the wheel. It turns out that I had only one client set up and that client was not published.. ie. I had a client called 'advertising' to cover all my affiliate ads. Since that client wasn't published, none of the ads worked..
Amazon and other affiliate ads are humming along nicely now.
Thanks Chris... felt bad about this sitting out there, but I'm just not a Joomla guy at all, as you know.
>>turns out that I had only one client set up and that client was not published
Ha! I spent probably an hour a few week ago trying to debug something. No matter what I did, nothing changed. I started throwing in echo and die statements and still, nothing happened. How was this file getting bypassed and yet the PHP error clearly stated it was causing the error? Answer: I was editing copy A and refreshing copy B.