I have a Web Application with Host Name Site Collections underneath. I am a Site Collection Administrator for each site.
I have another Web Application (Intranet) that is not a HNSC and I too am a Site Collection Administrator.
These Web Applications both sit under the same Application Pool.
For the HNSC, I am unable to Edit a Page in the browser (IE or Firefox) - I get an "HTTP 403 Forbidden" Error (see below). I can browse any page file, can edit settings, permissions, etc. The Intranet Web Application works fine and I can edit pages.
I'm a bit confused as to where to look to resolve this - SP permissions seem okay. Also, it used to allow editing so something must have changed at some point... Something in the IIS Site permissions?