CDF files that are dynamically generated through Active Server Pages (ASP) should insert the following line at the top of the file (before any CDF lines):

<% Response.ContentType = "application/x-cdf" %>

This ensures that servers return the correct MIME/content type "application/x-cdf".

Problems with CDF files being displayed as HTML text inside the Internet Explorer 4.0 browser, instead of invoking the subscription wizard, may likely be caused by the server returning the incorrect MIME type of "text/html" instead of the desired "application/x-cdf".