Opening a PDF file with Illustrator CS on OS 10.3
that was saved by Illustrator 9.0.2 on OS 9.2
may show an error message that fonts are missing,
or display the drawing with missing graphic elements
and other elements mis-positioned.

Illustrator complains about and substitutes for
text in the Textile and New Berolina font, even though
Textile is in both the Classic user Fonts folders.
Trying to change text to the right font doesn't work.

Opening the PDF file on OS9 and saving it as an
Illustrator format file gives a file that opens on
OS10 with Illustrator CS with no problems.