Axiom and Firefox (newbie)

I've just installed Axiom (downloads/axiom-ubuntu-jan2009-bin.tgz) in
/opt/Axiom/axiom/mnt/ubuntu as root and looked at the documentation.
I've read section 1.1 of bookvol11.pdf, so I typed (as normal user, in my home 
directory):

 export AXIOM=/opt/Axiom/axiom/mnt/ubuntu
 export PATH=$AXIOM/bin/lib:$AXIOM/bin:$PATH
 axiom -nox
  -> )set mes auto off
  -> )set out mathml on
  -> axServer(8085,multiServ)$AXSERV

and "listening on port 8085" appeared.
Then I started my browser, Firefox. I went to

  file:///opt/Axiom/axiom/mnt/ubuntu/doc/hypertext/rootpage.xhtml

but that does not work, i.e. after:
  Basic Commands -> Calculus -> Differentiate -> Continue
nothing happens and the Error Console displays:

"Security problem: contents in 
file:///opt/Axiom/axiom/mnt/ubuntu/doc/hypertex/rootpage.xhtml cannot load 
data from file:///opt/Axiom/axiom/mnt/ubuntu/doc/hypertex/127.0.0.1:8085."

"Errore: uncaught exception: [Exception... "Access to restricted URI denied"  
code: "1012" nsresult: "0x805303f4 (NS_ERROR_DOM_BAD_URI)"  
location: "file:///opt/Axiom/axiom/mnt/ubuntu/doc/hypertex/differentiate.xhtml 
Line: 119"]

Please, what am I missing?
Thanks
Sergio