Vista - email folders expand even with no email

I imported my email folders from outlook express (on an XP machine)
over to vista's windows mail.

I have a lot opf folders and subfolders and i do want them to expand
when new mail comes in,

But they seem to expand when there is no new email in that folder. I
collapse them, shut windows mail down and then open it again.

And the folders expand again - well sometimes.

I have gone over every folder and put mark all unread, then mark
read.

And i have turned off the option to expand when new mail and closed,
then reopnened and put it on,

But every so often they all expand. There are no rules that relate to
most of these folders.

So any solution? I don't want to have to turn off expand when new
emails as thats useful, but i spend ages keep collapsing folders.

Catherine