Untitled thread

hallo evryone

i have some problem with slackware10,
i have installed it under a lan with a porxy xp professional,,
All is ok,, i can reach server, i use mail and internet,
but i have only a strange problem,,
i cant reach some web site....
example i cant reach www.slacky.it, and some other,,,,
is a porblem of java virtual machine?
help me