I am getting the same error – when I click the browse all tab, i get a preview of the admin site. If I click on the Manage > Uploads, I see all of my thumbnails, but if I click on one of them to edit the page just loads the admin site. Is this just a problem with the latet build of WP? Can I try an earlier build and see if that fixes the issue? As a workaround I am trying the flickr photo plugin, but I would like to get the basic upload function working first! thanks