Question about Outlook Express

I'm using a MacBook Pro OS X 10.6.8, and Outlook 14.2.2

The unread message counter on my deleted items folder shows 5 more unread messages than are present. Consequently if my unread messages folder has 10 unread mails in it, the counter shows 15.

Even more irritatingly, when I empty the deleted items folder, the counter still shows 5

Is there any way to reset this counter?
Is there a configuration file which stores this number, which can be edited and therefore reset?

This is pretty minor in the grand scheme of things, but any help on this would be appreciated.

Thanks.