IIS 8 Express HTTP Error 404.3 - Not Found

Hi,

I have recently setup VS 2k12, Framework 4.5 is setup as well (I did a asp-regiis) from the 4.5 folder as I had some issuees running 1 website with the full IIS that I have on my dev machine.

Inside VS 2012, now my project is configured to run under IIS express 8 when I run inside VS I get the following error :

HTTP Error 404.3 - Not Found

The page you are requesting cannot be served because of the extension configuration. If the page is a script, add a handler. If the file should be downloaded, add a MIME map.

when I switch to old VS development server, everything works fine and I can browse correcly.

What am I missing