On my website I have several images showing, depending on the page.
The images are not locally stored, the html img tags reference remote servers.
The problem is that they don't always show.
Ive tried putting a random "?rand=123" value in the URL to prevent caching - no success.
If I copy the image links to another browser tab they show up and then refreshing the first page, the images come up immediately.
Well - difficulty to say anything about - but from my perspective right now it sounds more like a browser problem then anything else.
Is the behavior the same across different browsers and clients?
Try using FireFox (if you don't already) and install FireBug or similar tool and inspect the image elements which doesn't show the image correct, to see if there perhaps is something wrong with the image tag, which can help you debug your way forward.