Teapot

Unlucky... this is a mean little trick.
Basically what it does, is when you paste it into your name, MSN's servers cannot handle all of the special characters. It then immediately logs the unlucky recipient of the trick out, preventing them from using their MSN account again until they delete a certain file on their computer.

For Mac users, the file lies in:
C:\\Users\\[your account name]\\AppData\\Local\\Microsoft\\Windows Live Contacts\\[MSN address]\\real\\
Go into that directory and delete the file that ends in .Mecontact
This should fix the bug.

For PC users, the file lies in:
C:\\Documents and Settings\\[your account name]\\Local Settings\\Application Data\\Microsoft\\Windows Live Contacts\\[MSN address]\\real\\
Go into there and delete the .Mecontact file.

Hope this helps!