Well clearly you are a member cause I got this
If you are in a thread, and try to post down at the very bottom in the quick reply, making sure to click the 'Post Message' button below the window, does that work?
If, at the upper left top of a thread, there is a bottom labeled 'Post Reply' can you post a reply (like you can just post a 'test') in the new window that opens? Make sure you go below and hit the button 'Post Reply'.