ginge i sent you a bug half a day ago...
and I accidentally find that BetterMSN sometimes doesn't "follow" my sign-in action...that is, when I use account A to sign in, and sign out, then sign in with account B, the nickname and the status in BetterMSN are still of account A...and while that, at least the notification of "Somebody opened a conversation" disappears (not sure for other alert messages, since I uncheck the three checkboxes of alert options)...
I'll try to find how to reproduce this and give you more detail