I've been caught by this a couple of times now. (Not realizing that I am not logged in...) The site gives you the appearance that I am able to reply to a post. Click Reply and the post poofs away into the ether. At that time I realize that I am not logged in. The site should not allow that to happen. Or - it should take you to the log in screen, allow you to log in, and post the reply as usual.