Comment 5 for bug 973682

Temopary fix [workaround]:

1/ read [or mark as read] all items [markmfolder holding them as read]
2/ delete & recreate the Unread folder [maybe using option "rebuild" would do?]
3/ create your own top level folder & move all other folders into it.
4/ the top level folder now works as the "Unread" should be working!

voila - [appears to be] working ;)