Internet Explorer first downloads the HTML and then downloads the image files, two at a time. If all the images have not been displayed at the end of the fixed 5 minute time-out value, the remaining files are not downloaded. Pressing Refresh does not help, as it start the download from the beginning.
To work around this feature:
1. View a different page.
2. View the problem page. This causes IE to download images that are not in the cache.
NOTE: You may have to repeat this process if the page contains a very large number of images.