I figured it out. For some reason, the #flashcontent style element was screwing up my gallery, but only on IE browsers.
/* hide from ie on mac */
/* end hide */
I took out the #flashcontent element and it's fine now. Does that need to be there? What's the purpose of the 100% height declaration?
I also think the suggestion to update the embed to swfobject.js was helpful. I had two problems. One was the gallery not found issue, but once that was fixed, the CSS issue masked it.
Thanks for your help Ho!