If you cannot initiate session in Windows Live Messenger 2011 and the program reports error code to you 80048820 is because you have put a name in your profile with some invalid character (&, %, *, @, Ă§â€¦)
In Order to solve you only must it follow these simple steps:
1. Direct http://account.live.com/ here to you
2. It Initiates session with the account of Windows Live YOU GO affected
3. Information of account - > Name (of your user) - > Cambiar
4. It Keeps the changes and it reviews that the application does not generate problems to you in the beginning of session.