Is this email in the inbox ?

If so do the following:

Close OE
Search for inbox.dbx
Rename it to inbox.old
Start OE - a new inbox is created with an email about OE

If the old email in the Inbox is required:

Right click on inbox and select New Folder
Call it oldinbox and click OK
Close OE
Search for inbox.old
Rename it to oldinbox.dbx
Start OE, drag any emails that don't freeze from oldinbox to inbox.
Delete oldinbox with dodgy email that causes freezing.
Right cliclk on Deleted Items and select Empty