That's Internet Explorer, not Mozilla, aye. If it is set to medium, one should be able to stay logged in. Can you go to the "General" tab and click "Settings" under "Browsing History"? What is the value in the box next to "Disk space to use"? If that is above 50MB or so it should be of no consequence. In that case, you may wish to purge all cookies (In case one for the TMF has gone bad). To do this, go back to the "General" tab and hit "Delete" under "Browsing history", selecting "Delete Cookies" in the new window that appears. Try logging into the TMF with the "Remember Me" checked then.