In all of prosper style sheets font is set manually.
This is not good for users with non latin encoding, eg cyrillic encoding don't work
If change string (PPRdefault.sty:38) from
\usefont{T1}{ptm}{b}{n}\fontsize{20.74pt}{18pt}\selectfont\blue}{%
to
\usefont{\f@encoding}{ptm}{b}{n}\fontsize{20.74pt}{18pt}\selectfont\blue}{%
and so on
It will be encoding independent, and work fine.
