The new coding that was done to make the forums all sleek and pretty don't work on some browsers. I believe TurtleTrainer is working on making everything compatible with other browsers. On the computer I'm currently on I use Opera, and it works fine. It also works in FireFox and Chrome, as Krist stated. Do you have Internet Explorer or another browser by chance that you can try it on?
Also, as Krist said, try clearing your cache and cookies because that might have caused an issue. Let us know if you get it figured out, okay? :)