Window.open not working in IE8?

This is the JavaScript I'm currently using:

window.open('/modules/mod_oneononechat/chatwindow.php?key='+key+'&color=blue','x'+winName+'x','location=0,status=0,toolbar=0,menubar=0,resizable=0,scrollbars=0,height=375,width=420');

This doesn't seem to be working in IE8. It's a chat window that works fine on all other browsers (including IE7). Any ideas as to why it's not working on IE8?