Since the problem only occurs with a specific file, it's possible the file may be damaged in a way the the older version of filemaker tolerates but the new version does not.
Have you tested a recovered copy of the file?
The recover may report a problem with your file and this might explain things. The recover might fix the problem even if it reports no problem found.
Either way, you'll want to replace or rebuild your file if it turns out to be file corruption.
You could also test to see if a brand new layout that refers to the same table exhibits the same behavior--maybe one or more of your layouts are damaged.
Recover did the trick; wasn't aware of that feature. (File > recover)
You saved me a lot of headaches--thanks!