It appears that Reptile-Topsites.com has gone down, and because they have a picture on ball-pythons.net, it is saying you need to put in a username and password.

The easiest way to get around this is in FireFox. If you right click on the link at the bottom that says "Reptile Topsites", and then click "Block Images from reptile-topsites.com", you will no longer be prompted for a username and password.