Blank lines in Outlook Express

I use Outlook Express 5.0 for Mac as my email program and have this problem:

I have three blank lines in my Inbox list that will not go away, and in the folder list to the left there is a bold numeral three (3) beside the Inbox folder that indicates there are three unread messages in it. There is no content to these blank lines, i.e., double-clicking on them doesn't open anything. I cannot delete them.

What can I do to make them go away? I use an iMac with OS 9.2.2.

Thanks -- Jeff