Pictures not showing in XML Slideshow

Hi, I’ve created a slideshow (with external jpg loaded from an xml file) based on the Kirupa tutorial. At first it seems to work fine but after uploading it, some users couldn’t see the pictures. They seem to load one after the other but don’t appear in the slideshow. I thought the solution was to upgrade the Macromedia Flash Player which solved the issue for some users but then I realized the issue occuring for other users with updated Flash player.

Has anyone witnessed this problem and found a solution?

Thanks in advance!