Thanks for getting back. From the Microsoft site I installed: Windows 11 Pro, ver. 21H2, and OS Build 22000.318. This is the first time this error has ever happened and I've been working with large files in AFPhoto for years. It only happened with Publisher and not with Photo. The files I'm working with in Pub are large, about 750MB/spread with 20 spreads. Files are embedded and saved to external 1TB solid state drive. The laptop is a Surface Book 2 with a 500GB internal drive, 16GB RAM, i7 processor, and Navidia GTX 1050.
After looking through previous posts on this subject I assumed the file was gone so I've rebuilt the book and saved to Documents on the C with no problem and to the external drive. Since there has been no definitive answer as to why this occurred, I'm most concerned that it doesn't happen in the future. Can you shed light on this? What are your developers saying?
Thanks so much!