If you’re using a Mootools Accordion on Internet Explorer 7, sometimes it doesn’t open on item specified in show property.
You can simply fix this bug without using show property but calling Accordion.display method immediately after accordion creation, so you’ll get open item also in IE.
The problem with this is that it still shows the open animation. The “show” property is not supposed to animate at all, so this isn’t really a work-around.