Ah, sorry about that, I misunderstood what you were saying to me.
Well, go to Control Panel > Add/Remove Programs, scroll down to Windows Live Messenger and press "Change/Remove", then uninstall the software, do the same with Messenger Plus! Live.
Then go to C:\Program Files, and delete the "Messenger Plus! Live" folder and the "MSN Messenger" folder.
Now reboot the computer, and open up internet explorer (or firefox, whatever) and go to
http://messenger.live.com/ and download Windows Live Messenger, saving it to your desktop, then go to
http://www.msgpluslive.net/ and download Messenger Plus! Live, saving it to your desktop.
Now install Windows Live Messenger first, then after install Messenger Plus! Live.
This is a clean re-install and sometimes can sort out quite a few problems
.