Thank you for your post.
I don't know why FileMaker Pro 9 is unable to find the ending records. Have you tried a search just for the ending records?
One possible workaround is to turn off indexing (under Manage -> Database...), close the file, reopen the file and try the Find again. This will reset the index.
If you are still having difficulty, let me know, and I'll make arrangements to look at the file.