Using the validator with internal files

Newbie question ...

I used the upload version of the validator (http://validator.w3.org/file- 
upload.html) to validate a file which is on an internal net, and it passed. 
It provided the HTML for a link back to the validator ...

   <p>
      <a href="http://validator.w3.org/check/referer"><img border="0"
          src="http://www.w3.org/Icons/valid-html401"
          alt="Valid HTML 4.01!" height="31" width="88"></a>
    </p>

... which appears properly on the page, but when I click on it, I get ...

    Sorry, this type of URI scheme ("undefined") is not supported by this 
service.
    Please check that you entered the URI correctly. URIs should be in the 
form: http://validator.w3.org/

I'm guessing that the validator is expecting to see a www-style link, and 
is confused. How do I form the link using the path to a file on the 
internal net?