The method of including the file is the same, and you're correct, it's probably not that. But it may not be a server problem either.
The **only** time I experience this is when there's a dependent file missing and there is no error handling in the Flash to manage it.
XML file loads image paths and captions
Flash reads in XML file, builds array
When it goes to display the image, the image file is not present or is pointed to the wrong directory
Instead of the "red X" we're used to for missing resources, the Flash will just sit there, and the page will keep "loading" forever. If the Flash is coded properly, the caption should report "file not found" and continue after a time (or something.)
There are other similar situations that can cause this, but a missing resource won't act the way you'd hope with Flash.