Remove the MSN loginlist (passports):
- exit MSN
- go to start > run
- type: control userpasswords2 <enter>
- go to advanced tab
- click passwordmanagement button
- remove all passports you don't want in the loginlist (drop down box) anymore
Now restart your MSN Messenger an you will see you need to type in a password again, it will keep askin you too aslong as you don't tell MSN Messenger to remember you