If you use the latest versions of Firefox (>v23) and are having "issues" with photo Sets on Flickr, specifically with Flickr perpetually "Fetching more photos...", this thread offers the solution:
Flickr: The Help Forum: [Acknowledged] Flickr has issues with Firefox 23 beta
Short story: Go to about:config and toggle the value for security.mixed_content.block_active_content to False.
The "problem" is that Flickr is using javascript to load more images as you scroll down the page, and the new default in Firefox is to prevent that. For the most part, such antics have been used mainly for advertising, apparently.
Flickr - Firefox Conflict
Flickr - Firefox Conflict
Karl
Back on the trail, again...
Back on the trail, again...