The Outbox is probably corrupt.
Go to Tools | Options | Maintenance and see where OE is storing its files.
Close OE.
Go there with Windows Explorer and delete Outbox.dbx. With Win2K and WinXP
it will be a hidden file.
OE will create a new one when you reopen it.
If you think the Outbox may have messages you want to recover, instead of
deleting it, move, not copy, it to an empty Windows folder and then use
DBXtract to recover the messages.
DBXtract (free): http://www.oehelp.com/DBXtract/
