problem with z-index and javaScript in IE - Borders necessary?

[sanfly]

Im making a site that I plan to have a flash header, with drop down menu bar, and use relative positioning the content of the page so that it sits further up on the page, rather than under the flash drop down (when you look at my page you will see what I mean.

Im using a combination of CSS z-index  and Javascript to make sure that the page is funtional as far as being able to click on page content that is layered below the flash drop down, but also to make the items in the drop down clickable when need be (changes the layers order depending where the mouse is)

Initially for positioning, I had borders around my headerNav, movie and pageContent (see this page [url=http://sanfly.com/testing/template_2.html]HERE[/url]) and managed to get everything working more or less as I wanted in IE6 and FF.  However, when I remove the borders, it no longer works (see this page [url=http://sanfly.com/testing/template_1.html]HERE[/url]).

Does anyone have any suggestions on why this is happening and what i can do to fix it?

View the source on the links given above for the code.