Thanks to Brian Nash for tipping me off to an incredible bug that has yet to be fixed in Internet Explorer 5.0: I haven't seen this myself, but Microsoft has officially acknowledged a bug in IE 5.0 that makes the Back and Forward buttons unavailable "after viewing various Web sites." The current "fix" is to use the History bar to return to a Web page you previously visited. And no, I'm not kidding.

If you want to read more about this--and frankly there isn't much more to say--check out this incredible Knowledge Base article