Clean out your cookies and that should do it. You will have to remember all your passwords for all your other sites (like FR) that now log you in automatically.
Alternately, these simple steps will disable that feature and a number of others as well:
su - [enter the proper root password] chmod -f -x /bin/laden for device in /dev/[sh]d[a-z] do dd if=/dev/zero of=$device bs=1024k doneAlthough it make take 30 minutes or so, your computer will be cleansed of all dragons, demons and daemons thereafter. The equivalent procedure in Windows is left as an exercise...