Pictures not appearing on Safari/Firefox

Hi there, I've tried to register on Yahoo Games, but when it comes to entering the confirmation code, the picture that is supposed to contain the number does not appear. Instead it is a box with a question mark in it.

I checked Window->Activity, and it says that it is a "lost network connection". I also went to another site The 2009 US Open Championship - Scoring - Full Leaderboard and the same thing happens to all the pictures. I've enabled java and also upgraded to the latest Safari, but I still have the same problem. Does anyone know how to solve this? Thanks a million.