[jQuery] Problem with window focus event in Firefox 3.5/Win Vista?

Hi folks,

I'm having a problem using:

jQuery(window).bind("focus", function(event) { alert("test"); });

in Firefox.

I'd expect a single alert box when I focus on the window. However in
Firefox I get 4 alert boxes in a row?

IE6, 7 and 8 are fine with this and produce the expected, single alert
box.

Any thoughts as it's rather annoying.

Cheers!
Paul :)