Today, I spent most of the day chasing font problems when trying to create a pdf invoice, amon them the one talked about here http://support.oranged.net/entries/20664947-problems-with-font-when-send-pdf-with-mac-mail and another one that showed itself as a error msg about a font and the msg "glyph not found".
This error msg comes up when even a character cannot be displayed properly in the pdf. In this case, I had copied over the text from another pdf file using copy/paste. There were several Umlauts (ä and ö) in that text but only one of them (a ü) produced the problem which is why it took so long to find it and why, in the end, I decided to report the problem here.
If you get this error, check your special characters...there just might be a single char somewhere in your text producing this error.