Total HTML Converter: On Mac some letters are invisible in generated PDF

A customer who loaded a PDF generated with Total HTML ConverterX wrote us: He uses an Apple Mac with OS X 10.6.4
The Mac-Reader "Preview" shows the PDF correctly, but when he prints the document all 'o'-Letters are not printed but leave blanks.
When he opens the stored PDF in Acrobat professional/Mac 8.2.2 or Acrobat Reader the 'o'-Letters are invisible already on the display.

Maybe there is a problem with the embedded fonts? Is such an issue known already?

Dear Ulrich Eickmann-Martini,

Our programs run only on MS Windows®2000/XP/2003/2008/Vista/Windows 7.

My issue is not about generating PDF on Mac with Total HTML Converter.
the problem is to view the generated PDFs on Mac

Dear Sir,

Could you send your PDF and HTML files to support@coolutls.com? Our developers will investigate this issue.

Thank you in advance.