Hi,
I had a similar problem with Shadowbox 3.0b or rc1, in my case it was working perfectly with any browser but not ie7 (it works with ie8).
I had to init the Shadowbox libraries one the dom was loaded completely.
Debugging the SB code showed that the DOM object was not initialized correctly so I had to do something like this:
function initChatBody() {
var options = {
language: "en",
players: ['img', 'html', 'iframe', 'qt', 'wmp', 'swf', 'flv']
};
Shadowbox.init(options);
}
YAHOO.util.Event.onDOMReady(initChatBody);
I am using YUI as you can see.
You could also use window.onload
Hope it helps
Giuseppe