It could be related to the email address you use. If I recall correctly, the email address you used when you signed up is your user name here. If you are now using a different address, the site won't recognize you as a registered member. I'm not sure how having two addresses affects the behavior. The email you use for discussion notifications, btw, is not visible in the forums, but it does appear in the email notification another user receives when you reply to a post. That let's members communicate directly without exposing our users to bots searching the web for addresses to spam. Why not write up this problem using the "Forum problems or suggestions?" link in the upper right of the page. Everything there is sent directly to Chris, and I'm sure he can sort this out for you in a jiffy.
"The Lion shall lie down with the Lamb;
but the Lamb will not get much sleep..."
Lazarus Long