Mongrel and content type

I set up an apache2 + mongrel clusters.

Everything is working fine except that IE Explorer when I try to see a
page of my site it tries to download it instead of showing it.
Firefox and Safari are working fine, I have also checked the content
type in the headers sent by the server and they are correctly set to
The url the application is serving are without any extension e.g.

I guess that there is a problem with content-type setting but I can’t
really realize what I have to configure and why it’s happening only in

Any idea?