w3.org error with Mozilla Firefox v1.5.0.7

Hi!

When I try to access to w3.org web site with Mozilla Firefox v1.5.0.7 I get 
this error:

Error de lectura XML: mal formado
Ubicación: http://www.w3.org/
Número de línea 546, columna 77:<a 
href="http://validator.w3.org/check?uri=referer" shape="rect"><FONT 
size=1>[AD]</FONT><AD- 0" alt="Valid XHTML 1.0!" height="31" width="88" 
/></a> <span class="whiteout">|</span> <a 
href="http://jigsaw.w3.org/css-validator/" shape="rect"><FONT 
size=1>[AD]</FONT><AD- lt="Valid CSS!" height="31" width="88" /></a> <span 
class="whiteout">|</span> <a href="/WAI/WCAG1AA-Conformance" 
title="Explanation of Level Double-A Conformance" shape="rect"><FONT 
size=1>[AD]</FONT><AD- 31" width="88" src="/WAI/wcag1AA" alt="Level 
Double-A conformance icon, W3C-WAI Web Content Accessibility Guidelines 1.0" />
----------------------------------------------------------------------------^

With IE 6 it goes fine.

Any suggestion?

(Sorry by my english).