All you have to do is create a web page on a free site that contains nothing more than a page that automatically redirects to the crash link. Then link that page in your message.
In fact create a PHP file on your web server that contains only this one line:
Call it "crash.php" (or whatever you like). Then just send a hyperlink in your message in this forum and it will crash susceptible windows machines. I just tried it and it crashed my Win98 machine...
Note: for the above to work you have to obviously be using a PHP capable web server. You can also use other methods of redirecting, like JavaScript (I turn JavaScript off by default so you wouldn't get me even if I did use Windows to surf the net, this PHP script will work even with JavaScript turned off). You can also use an HTTP-EQUIV statement. Search the web if you don't know how.
Of course this will not crash a Linux browser. This is what I get when I try to open the page with Konqueror:
[ June 10, 2002: Message edited by: VoidMain ]