Corrupt images

I have built some apps for a site, originally in Flash CS3. I have brought these files into CS4 and made some slight changes to them, saving in CS4 format. It is programmed in ActionScript 2.0

The problem is, if you let the site run for an extended period of time, like overnight, many of the images show up as a red box. Example:
http://myflashdesign.net/sites/corruptImage.jpg

Some of the red images are in the Flash file itself, and some are loaded dynamically.

I am not sure what is causing this. Is it because I saved up from CS3 to CS4 format? It doesn’t seem to be an issue with compiling the movie, since the dynamically loaded images are getting that effect too.

I had not soak tested it prior to saving it in CS4 format, so I am not sure if that is the sole issue.