Shoutbox

I strongly recommend you get MSN Messenger 7, as it fixes important security problems. Also when you use 6.2 you will just get pestered to update whenever you use it.

Uninstall MSN Messenger and Messenger Plus > Reboot your computer > Download and install them both again. If you really want MSN Messenger 6.2, but I really suggest you don't you can get it from here.
When you first uninstall Plus, I recomend you keep all your settings.

Also make sure you get the latest version of Messenger Plus (3.52.130)