are you talking about msn messenger or windows messenger, because if its windows messenger then its not always good to touch it because its apart of windows so you could just rename it to messengerOFF, that way it will never open even if you double click on it !
What I would really like to know is how to disable messenger from storing my passport sign-in altogether. Removing my passport info every time I use messenger is becoming a drag. I'm assuming there must be some registry key that can disable this feature. Any takers on this?