All the default HTTP page returned (for instance HTTP 403) must be refreshed to
some clean HTML and XHTML page that will pass the w3c validator.
Page encoding has to be fixed, using UTF-8 everywhere and under firefox 1.5 b36
returns '?' instead of any diacritic sign enabled letter like Ã© Ã¨ Ã ...
Choosing XHTML 1.0 Transitional and encoding the page in UTF-8 as well might be
a good choice for their compatibility "good citizen" known behaviors.