Nothings there, but something shows

Hello, In Windows XP Pro and Outlook Express 6.0. The Inbox is empty but down in the status bar it shows 1 unread. When I have several in the inbox and 1 is unread the status bar shows 2 unread. Is there such a thing as an invisable e-mail that you can’t open or delete if you can’t see it ? Spooky ghost inside my PC, any ghostbuster help would be grateful…Kenny