You can remove your passport from the list by going to tools > options > general..under sign-in accounts and passwords click "change". Remove your passport from that list.
Or:
- exit MSN
- go to start > run
- type: control userpasswords2 <enter>
- go to advanced tab
- click passwordmanagement button
- remove your passport
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
/ 
