Mp3tubetoolbar site keep appearing as homepage?

I am one of several users on my computer (and an admin). Apparently all of the users have had a problem with their Firefox homepage being changed to mp3tubetoolbar.com, and even if we change the homepage it just reverts to mp3tubetoolbar after a restart. Is there any way to prevent this? Can't find an uninstall for it, which is also a problem.