There could be many reasons for this, but first let me try to clear up any confusion between the forums and the community features on this site.
Please understand that the forums are a separate thing entirely from the new davidphelps.com website. So if you already have a forum account you need to go to http://forums.davidphelps.com and sign in with your old username and password. If you have problems logging into the forums or forget your password please use the forgot password links on the forums and not on the main website. (This is important as the forgot password function on this site won't help you with the forums)
The website login is completely separate and will not give you access to the forums when logged in. It is for the community sections on the main website only (leaving comments, etc.). Resetting the password on the main site will only affect your login to the main site.
If you are still having problems please use the comments/suggestions link at the bottom of the page to report your problem and we will get back with you as soon as we can.