2
They will rotate automatically. I have found that from time to time, banners will sometimes display more then once, making it appear as though they arn't rotating.
SHIFT+Click your refresh on IE and it should work as well. This will force the browser to download a fresh copy of the page and code output.
Either way, your banners will rotate if all the settings and links are correct. A word of note, they won't rotate untill you go to another page, or refresh your current page. Sorry if I confused the matter...