I did a whole day in researching the problem. It seems to be an issue related to load() and IEs and Safari when images are already cached. If the images are already cached the load won't firing the callback function respectively load() will not fired.
But I've found the onImagesLoad plugin: http://includes.cirkuit.net/includes/js/jquery/plugins/onImagesLoad/1.1/documentation/index.html This plugin seems to handle the »images-load-cache-problem« correctly in all tested browsers.
