That's great! May I ask which comma it is?
A lot of people report that their iWeb created website but also non iWeb created websites don't display correctly in IE. It is just a code however all browsers have to read that code, understand it and render the code (display to you what the code means=>ex. slideshow).
Different people talk different languages. They may know some languages better than other. Same for the browsers. Some do a better job on some languages (codes) others at other.
More info here:http://iwebfaq.org/site/iWeb_Compatibility.html
InternetExplorer 6 and 7 perhaps don't always understand the z-index which is responsible of telling which object is in front of which other object when there are multiple layers.