Flash site won't navigate on Macs (help!)

I’m really quite desperate, so any help would be greatly appreciate. My website (www.naosrendering.com) will not navigate on macs. I created the site based on a variation of the Web Site tutorial (http://www.kirupa.com/developer/mx/full_site.htm). I don’t own a mac, but from what I’ve observed on other people’s machines is this: the stage with the navigation button loads fine, and the first swf loads into the mc as it should (loaded from an AS on frame 1), but when you click on a button the movie you expect to be called isn’t. I know the buttons work because they’re designed to allow the currently loaded movie to complete before the next one gets loaded, and it does.

This functionality is the biggest difference between my site and the tutorial. Instead of directly loading the next swf, each button assigns a variable and then allows the currently loaded movie to continue. When the movie reaches its end it checks the variable and then loads the next movie accordingly.

But it works on a PC!!!
Source files provided upon request (gladly)