[R] help.start() doesn't work

[Andreas Zocher]

I installed the latest R-package "R-2.1.1-1.rh4AS.i686.rpm" on a Red Hat
Desktop 4 (RH EL4) machine. When I try to get help by the help.start()
command an error message appears:

-----
> help.start()
Making links in per-session dir ...
If '/usr/bin/mozilla' is already running, it is *not* restarted, and
    you must switch to its window.
Otherwise, be patient ...
sh: /usr/bin/mozilla: Datei oder Verzeichnis nicht gefunden
sh: /usr/bin/mozilla: Datei oder Verzeichnis nicht gefunden
-----

The firefox browser is installed in "/usr/lib/firefox-1.0.7" by
default. 

How can I change R's browser path?

Thank you.