A script was being triggered "OnLayoutExit". I inherited that script from the sample invoicing solution provided by FileMaker. Its job was to capture some screen-size info about that layout for later use. Since I custom-size each layout in the script that takes me to it, I figured I didn't need the "Capture Layout" script, and so I deleted it. THAT was the one FileMaker was looking for and not finding every time I tried to move to a different layout. In retrospect, I realize that the bizarre error message was only appearing as I was trying to move between layouts — including when opening and closing the file! That should have been my tipoff!

Everything works just slick now, and I've learned something. Hopefully others did as well.

I love this list.

Beaucoup gratitude to you for aiming me in the right direction, Stephen.