Maybe the return just isn't large enough for IE to show you what was returned. I think short responses are somehow considered incorrect by IE. If it works in Camino, maybe you can see just how big the response is.
I initially found the problem using tclwebtest which uses tcl's http module and no data is returned at all. In Camino a full page is returned (the site-map page). I'm thinking that maybe I've got something misconfigured or something, so I wanted to see if anyone else was having the same problem.