preventDefault() fails in IE8?

preventDefault() fails in IE8?

jquery-1.4.2.min.js

I'm trying to use the Alt+keyCode in my web-app and want to prevent the event from bubbling up to the browser.

The following works fine in FF & Chrome, no event propagation, but fails in IE8:
  1. $().ready(function() {
  2.       $('html').keydown(function(event) {
  3.             if (event.altKey) {
  4.                   if (event.altKey && event.keyCode == 83) { // 'S'
  5.                         save();
  6.                   }
  7.                   event.preventDefault();
  8.             }
  9.       });