OWA Log Off Button

If I click on the Log Off icon, a logon window pops up requesting my id, password and domain, with two buttons on the bottom: OK and Cancel. If I click on OK (with or without filling in my id and password) I then get to the correct log off reminder screen. If I click on Cancel, I get an error message about “Access denied.” At that point if I use I.E.’s Back button to go back to my mailbox and click on theLog Off button again, then it works and takes me directly to the reminder screen. Can anyone suggest how to fix this? Thanks!