Problem resolved -- another mystery
Thanks for that advice. I have been working very diligently to learn as much about DOM as I can digest. I have it interspersed in my code, but the learning curve is extremely steep! It will be a gradual process... there is only so many hours per lifetime!!
The document.write was only for testing -- It seemed to do what I was trying to accomplish, but it was very preliminary and js came to the rescue -- I found a very cool way to accomplish the same task without additional php files/scripts.
As it turns out, I did some recoding and the pop-up went away. I wish I had some idea what had caused and then corrected it. I keep earlier versions of my work but the format of the open statement is exactly the same. There must have been something else causing that problem.