It might be doing what it does on my computer...a pop-up menu appears but it appears somewhere silly, like way, way, way at the bottom of the page.
I've found that in the latest versions of Internet Explorer, both in OS 9 and OS X, when I click on someone's username, the little pop-up menu appears far below the bottom of the content of the page, and when I mouse-over it, it disappears before I can click on it. GRRR.