[XeTeX] XeTeX cannot find very common fonts in the system

[André Bellaïche]

These simple commands

\documentclass{book}
\usepackage{osxfonts}
%\renewcommand{\encodingdefault}{U}
\NewOSXFontFamily{nff}{Garamond}
\renewcommand{\rmdefault}{nff}

do not work. The error message is :

! Font \testfont=Garamondat10pt not loadable: Metric (TFM) file or  
installed fo
nt not found.

The same happens with Adobe Garamond, Times, Times Roman, Helvetica,  
Utopia, with and without the command "\renewcommand{\encodingdefault}{U}

I use teTeX with TeXShop, and I have reinstalled XeTeX vie i- 
installer, half an hour ago. To typeset, I use the XeLaTeX button. My  
TeX system could not find the osxfonts.sty file, but I found it in  
XeTeX_doc/Samples.

Other informations: Mac OSX version = 10.4.8.

Of caourse, I have noticed the lack of a space in Garamondat10pt, so  
I have try to type {Garamond }. This makes no difference.

Could somebody give me some help ?

Thanks,

André Bellaïche