Why can I browse my asp.net website through the iis5.1 admin console and not through IE 7.0 ?

Hi;

I am unable to see my default page when I enter http://localhost/mywebsite,  just an HTTP 404 message.

And yet when I browse the site from the IIS admin console I can see my web page no problem ?

I tried adding this to my hosts file localhost mycomputername and it did not help.

Thanks for any insights !