Vista - Unusual Layout of Folder window

Without my intervention, Windows Mail has provided me with a different layout
to the folder window. Let me explain ..

What I now see in the (left hand) folders window is a small tree that has as
it's root "Local Folders". Under that are two sub options which are "Inbox"
and "Microsoft Communities".

If I click on "Inbox" then I see my inbox mail listed in the right hand
viewing panel.

If I click the root item, "Local Folders", then I get what I call the folder
list, but in the right hand viewing panel. This folder tree does not permit,
collapse or expansion of the sub-branches.

What has happened here ? How do I get back to my old view which showed my
folder directory in the left hand panel (traditionally my folder list), and
the contents of the highlighted folder in the right hand viewing panel ?

(In the interests of clarity I will state that I have the show preview pane
option switched off.)

Any help gratefully received.