Photos linked from photobucket are served right from photobucket.
Your browser pulls them from there if the link is correct.
You can check the link by clicking reply on one of the posts and then switching to text mode with one of the buttons on the right side, just above the edit box.
If you cut and paste that link I to a new window and it works, then there might be something on the forum side of things, BUT if that were the case, it would affect everyone. It could still be a browser thing on your end. Try clearing your internet cache and see if that helps.