Shoutbox

Go to the control panel> add/remove programs> MSN Messenger 7> Remove.

Remove the MSN Messenger folder in C:\Program Files

Remove the MSN Messenger folder in C:\Documents and Settings\<user>\Application Data\Microsoft

Remove any other folders which point to the MSN Messenger folder in program files.

The next stage is very dangerous if you don't know what you are doing, so follow the instructions carefully and don't delete anything else.

Start> Run> type "regedit" (without quotes)> Locate to:

HKEY_CURRENT_USER\Software\Microsoft\

and

HKEY_LOCAL_MACHINE\Software\Microsoft\

Then delete the folder called MSN Messneger or something like MSN Messenger.

Then reboot your computer.

Download MSN Messenger from http://messenger.msn.com and install it.

NOTE: When deleting your folder in Application Data, you will lose all  custom emoticons, backgrounds etc. You can use MSN Backup to backup these things.

Should fix your problems