Sounds like either your file or an index associated with that file is now damaged. Do you have a back up copy of your file that does not show this error?
If so, it would be best to revert to that back up. You may need to save a clone (which will have no records) of that file and import all records from your most recent copy into that clone.
Coincidentally, importing the records like this builds all new indexes in the target file.
That isn't what I wanted to hear! :) But at least I do have a month old back up that seems to be working correctly.
Since I don't do updates to FM Pro or change much of the workings of the database, my husband wondered if updates to Windows would affect the compatibility of this older program?
While there is never a guarantee that an OS update won't affect an installed application on your computer, it's not likely and it is very unlikely to produce the specific error condition that you've encountered here.
Ok, thanks for the info.