cant join Archon Prison

hello,
i can join archon server (pvp.thearchon.net)
but when i select prison, my minecraft crash with the error in attachement.
they say its my minecraft, so i send you a copy of crash in attach.
what can i do to resolve this problem.
its the same in diferent versions on minecraft, and diferent computers.
the support of server say that dont know how to resolve

thanks