The Content-Type problem...

Hello!
   I have a rails 1.2 application which I recently ported to Rails
2.02. I added a mapping in the routes.rb file like this:

map.resources :accounts

Next, I implemented the

  respond_to do |format|
      format.html {render :text => @account.to_xml}
      format.xml {render :xml => @account.to_xml}
      format.json {render :json => @account.to_json}
end

thing. When I browse the following URL,
localhost:3000/accounts/1.xml

Then the page is rendered in plain text though if we view the source
of the page, we can see the pure XML generated by our application. But
why the browser is rendering it as plain text instead of showing it in
a tree structure as usually Firefox do.

However, if I create a new Rails application from scratch, it behaves
as expected. What might be wrong?

Please guide me in this regard.

Note: I use Firefox 2.0.0.11

Regards,
Mohsin