Thanks for responding, Mark. I conducted a little experiment (I never learn!) and what I did was search for all "infos.txt" files and delete them. Apparently these are generated when you choose "create index files" from the browser. With these files gone, everything sorts on-the-fly as it should now. It seems once I create an index file, all entries are frozen in their current order and no further sorting is possible. All subsequent additions to the browser category will be added to the end of all other entries regardless of it's sorting position. Weird. The only reference to the list on the left hand side of the browser (Sky, Landscapes etc.) is in Carrara.Priv so maybe there's an answer there for that. Maybe some cut and paste will fix things. 

John