I am trying to use .html as the friendly url extension, set through Site manager > Settings > URLs & SEO, but it makes all pages on my site (except for the homepage) produce 404 errors.

If I set it to use .aspx instead, it works fine.

Furthermore, if I set documents aliases that have a .html extension, I get a 404 error for those too.

For info, I'm currently have Kentico running on IIS Express 8.

Any clues on what I'm doing wrong?

Thanks,
Joe