[OS X TeX] problem with \renewcommand{}{\arabic{}}

[Fabienne Goldfarb]

Dear all,

I am a new member of the list and I have a problem I hope some of you  
can help me to solve
I recently moved from an PowerBook to a MacBook and thus I reinstalled  
LaTeX. I used MacTeX2008, and nearly everything works, except a bug  
with numberizing with arabic numbers. I use the following commands in  
the beginning of my TeX files : \renewcommand{\thechapter} 
{\Alph{chapter} -- }
\renewcommand{\thesection}{\Roman{section} -- }
\renewcommand{\thesubsection}{\Roman{section}.\arabic{subsection}}

the last one doesn't work : instead of numbers, I have  
"subsection ...." (it is written "subsection" instead of the number as  
if the counter doesn't work). I have the same problem with the figures  
numbers if I use \renewcommand

If I use the command \roman instead of \arabic, it works.
If I don't use the \renewcommand it works also (but I don't want this  
way of counting the subsections)
And if I use the same file on the PC I have at work (with MiKTeX), it  
works too so it is not linked to a badly written command.

I redownloaded macTeX and reinstalled. I "cleaned" my computer with  
Onyx. Reinstalled again MacTex. It still doesn't work.

Thanks for your help

Fabienne Goldfarb (from France : sorry for possible english mistakes)