Actually there's no DOCTYPE on the page with the cMotion script. And, if viewed on its own in any browser, it acts oddly. I'm talking about the /content/reviewslouise.html page. Once it gets going it's OK. But at first it either jumps or overlaps itself.
Perhaps if you fixed it, you would have better luck with it. I may do more testing when I have more time.
Also, if you remove the absolutely positioned container for the iframe (on index2.html):
Well that messes up the layout, but fixes the problem of the cmotion being slow in IE.
<iframe src="http://www.louiseleconte.com/content/reviewslouise.html" style="border-width:0px; border-style:solid; border-color:#E0DBD3;" width="1200" height="650px">
<p>If you can see this, your browser doesn't understand IFRAME. You need them to visit this website... we are sorry. Try from another computer.</p>