>You can run ASP pages and ASP.NET pages for the same web site. The probelm here is that you are using a common html file that contains specific code for classic ASP. You would need to create a separate html file that does not contain any code specific for a target page type.

Yup, that's what I ended up to do. I have copied my Header.html file into another one. For those ASP pages, I call Header2.html instead.