The flying pdf export plugin (version 1.7 and earlier) creates the pdfs for export in a temporary directory on the form pdfexport-20100517-17May10-0917AM-1 this is locale dependent as Japanese and Russian locales will write the appropriate characters for the "AM". This means that either the file-system can not handle it (unlikely but a risk), and confluence will strip the multibyte characters from the url, leading to a HTTP-403. We should not have any language dependent parts in the directory names.