Well, this time I'm quite impressed, via just one simple line of code you can crash IE:

<input type crash>

Put that in a text file and name it .html, viola, must be one of the easiest ways to crash Explorer.
Need I say [URL=http://www.opera.com/]Opera[/URL] is not affected? A fix is not available yet but you can [URL=http://www.securityfocus.com/archive/1/319360/2003-04-20/2003-04-26/0]click this link for more information[/URL].