problem with locale

[Guill. Moreno-Socias]

   Hello.
   I would like to know how to reset everything around the locale in the
system.
   Background:  I had FreeBSD 5.4, everything was working fine.  Then I
upgraded to FreeBSD 6.2 and the locale became corrupt.  I have since
downgraded to FreeBSD 5.5 (because of a horrible problem of "em0: watchdog
timeout -- resetting"), and the locale is still corrupt.
   Examples:  any "man" command gives

ctype locale: Invalid argument

and "perl -e ''" gives

perl: warning: Please check that your locale settings:
        LC_ALL = (unset),
        LC_CTYPE = "fr_FR.ISO8859-1",
        LANG = (unset)
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").

(please note that this is NOT a perl question;  the preceding example is
only to show the problem).

   Thanks in adavnce for any help.

-- 
Guillermo Moreno-Socías