Does anybody else have this happen?

MSN Instant Messenger is installed in a machine I share at work, and any time I go to an MSN site (example: Hotmail) it appears in the System Tray by itself. I have to manually shut it off again because I don't want all kinds of extra crap running in the background. Even if I do this, if I go back to an MSN site, it appears again!

Anybody know of a simple way to prevent this happening? I can't uninstall it, unfortunately...