Today at work Sharepoint was blocking access to Internet Explorer. Something like about:protectedmodeoff. I could look into it, do some searches and figure it out. But it was just quicker to tell anyone affected to download Firefox Portable, which worked.
Another interesting feature: when connecting to the Exchange server in IE it automatically logs in to your email. Which is great until you want to log in to access a different in-box, because you can never log out… EVER! Oops, Firefox time again.