I shall upgrade to 3.1 and see what explodes.
ok, now running.
1 - windows live writer 2011 seems to have issues with media files.
not tracked this one down yet, might be pilot error.
the file I was attempting to attach just disappeared quietly.
2 - media files.
somehow I added a file "pyon_s2.png" twice.
go to media files in weblog, delete one,
the thumbnail disappears. leaving the empty box.
attempting to delete it again generates a 500 "unexpected exception"
object null is not a known entity type.
3 - media files 2.
with the remaining one from above, if I click on "post in weblog"
it goes to the editor, but no clues as to where the image has gone.
(may or may not be an error)