I also made a new thread because its the ONLY way I can post.
As you can see many people are having the same issue. The "Reply" button does NOT work for many forum members. I can make new threads, but cant reply to existing threads. Its been like this for MANY months. I still peak at the site once in a while but its clearly a problem for a large amount of the community because this forum is very dead.
In fact the problems are so bad with the xbox.com that it caused issues in Forza 3 with the "My Forza" button. That button was linked to this site and the gamertags. T10 had to change the layout of their entire forums because the game no longer linked to the gamertags. Luckily T10 figured out a way around it.