HTML Validator: uploaded html files not recognized

Hello helpful W3C folks: 
 
I usually upload the pages of my website from my machine to the W3C HTML
Validator before uploading them to my site to make sure it validates. Today
when doing so I got the following message:
 
"Sorry, I am unable to validate this document because its content type is
text/plain, which is not currently supported by this service. 
 
The Content-Type field is sent by your web server (or web browser if you use
the file upload interface) and depends on its configuration. Commonly, web
servers will have a mapping of filename extensions (such as ".html") to MIME
Content-Type values (such as text/html)." 
 
This is happening ever since I upgraded to XP Service Pack 2. I am usinf
version 6 of IE.
 
The upgrade seems to have broken something. Is there a way to set MIME types
in IE so I can validate pages from my machine like before? The following
link addresses the issue but, in typical Microsoft fashion, fails to provide
an answer.

http://msdn.microsoft.com/library/default.asp?url=/workshop/networking/monik
er/overview/appendix_a.asp

Thank you!

Gerhard N Ade

http://www.gnade.com/