Cross Platform XML issue

We recently launched a micro site for a client:

The site works perfectly on a PC on all browsers, but on a Mac the thumbnails for the different bunches of videos doesn’t show up. This is the first decent sized project we have taken on with AS3, and this is the first cross platform issues we have run into in years doing flash.

All of the content is pulled from an xml feed and we are stumped why the thumbs show up on a pc and not a mac on the web when all the development was done on a mac and runs fine locally.

Any help would be appreciated