Resource types

Hi there, when I try to insert an image file while updating a resource with the HTML editor, the insert image dialog box allows me to upload the image from my local directory to the server, but even though there is a label "file browser" in the dialog box, the area where the server side file browser should be is blank. 

From top to bottom in the dialog box, there is window for the url of the file to be inserted, an "alternative text" window, a large blank area with the label "file browser" above it, a "preview" window, and the upload browser(complete). 

The files definitely upload, I can browse through the site to the files.php/1/images folder and find them there, so the insert image dialog is functioning insofar as you can upload through it, and - once you deduce the url for the uploaded image - insert it, but for some reason the server-side file browser is absent, even though there's clearly a space for it.

Please, can anyone suggest a remedy?