HI Con --
Well, the problem went away more or less by itself. I created a new file, copied and pasted the entire old file, and it compiles with no complaints.
I opened the old file with a text editor that allows the user to display any file as hexadecimal. I looked at the start and end of the file for any characters that didn't belong. There were none. The file is too big to look at very much.
Along the way, the person who wrote the first file sent an update that had exactly the same problem, so there could still be something out there.
Anyway, it's gone now, so on to the next issue.
Thanks for your help.
Gary