You may want to use at least 10.2 (mandriva 2005) or even 2006,
or wait for 2007
Not sure how to deal with your webmin error
try service webmin stop
then drakconf
Would be tempted to do as root a removal of webmin
urpme webmin (check syntax)
>>Perl_Gthr_key_ptr
Sounds like you have installed a library or perl that is
not a compatible version with draks
Another way is to use command line to try download
with urpmi (have you got it configured) drakconf and perl (and whatever
you have messed up). You could also do a force install with rpmi
of perl and drakconf etc from your dvd/cd
I feel I am not giving you fantastic advice...
If above this fails, I would be quite tempted to install mandy 2005 really (at least), provided you have /home on a separate partition,
and not too much to loose (do some backups)