Lost page thumbnails

[2e]

Working in Word 2007 on XP on a PC. I am writing a huge document (a novel)
which I navigate around using the page thumbnails. I have never been able to
get the 'document map' to work as it should so I use thumbnails to navigate
by making sure the heading 1 and heading 2 are styled big enough to be
readable on the thumbnail. It is vital I have some kind of effective
navigation system as I jump around in the document so much.
But suddenly I have lost the ability to see the thumbnails. Can't see them
in any view, (print or draft). When I click the checkbox on the view
show/hide section nothing happens.
It is the same with all my documents now - not just the novel. Tried
re-starting the computer - no change to the problem.
This problem has brought my novel to a halt! Tui

 

[2e]

While I'm at it, why does the document map not work? I have formatted the doc
with heading one and heading two all the way through but in the document map
pane, only a few of the headings show up so it is useless to me. I need to
see all of them.
If I could get EITHER the document map OR the thumbnails to work it woud be
great but the thumbnails are better really as they show me quite a lot more
than the document map can.
I am a pretty experienced computer user having been building web sites since
the web was new but obviously not beyond making stoopid errors and being a
bit blind.