Comment 2 for bug 790014

I frequently have this problem as well, also with the unread counter on top of the list: xx unread, xx total

Choosing show 'Unread Messages', shows the 'unread' messages. But they are read (and shown as read as well).
Selecting them and marking them as unread and after that marking them as read, mostly fixes the wrong unread-counter
If that fails (sometimes) selecting all messages (in All Messages view) and again marking them unread and read again, always fixes the wrong unread counter.

It seems that it has something to do with me having read the messages on another computer at work (the unread messages problem then might happen at home for the same email account)