Firefox 3.6 - Referer Problem mit W3C

Nach Installation des jüngsten Updates für FF bekomme ich bei Aufruf von W3C über den Bilderlink in meinem Impressum folgende Fehlermeldung:

No Referer header found!
You have requested we check the referring page, but your browser did not send the HTTP "Referer" header field. This can be for several reasons, but most commonly it is because your browser does not know about this header, has been configured not to send one, transferred the referring document over a secure protocol such as https but is accessing the validator over ordinary non-secure http, or is behind a proxy or firewall that strips it out of the request before it reaches us.
This is not an error in the referring page!
Please use the form interface on the Validator Home Page to check the page by URL.
Valid XHTML 1.0! The W3C Validator Team

Ãœber IE: Kein Problem. Versuch. Mozilla zu erreichen, gescheitert.
Problem ohne Prio- aber ärgerlich. :thumbdown: Wer hat ne Idee? Fritz