validator.w3.org and Windows XP SP2

Hello

I am having problems using the W3C Markup Validation Service with Internet
Explorer with Windows XP Service Pack 2.

When using the Validate by file upload feature I get "Sorry, I am unable to
validate this document because its content type is text/plain, which is not
currently supported by this service."

If I do the same thing in Mozilla (on the same computer) or Internet
Explorer 6 on Windows 2000 SP4 with the same file it works fine.

I've tried it on 3 XP SP2 computers and get the same thing.

Regards

James Carey