If they're old photos, it may just be that the people whose photos they are may have deleted them from the servers!
An idea - if you post again with the URLs of some of the photos you're having problems with (right click on the space, left click on Properties, then copy the URL from the box) - or the URLs of some of the pages that you're looking at - we might be able to have a look and see if we have the same problems. If we do, that would suggest that it's just that the photos have gone, not that you're doing anything wrong.