If you haven't noticed yet, there is a slight alteration of the forum's URL:
Message from Patrick Clinger, President of ProBoards Forums:
For quite some time now, ProBoards forum URLs have included the server number (#20) in the domain name (e.g. hwi.proboards.com/index.cgi). ProBoards are happy to announce that all forums have been seamlessly upgraded to numberless URLs.
When accessing your forum through it's normal URL you will be automatically redirected to hwi.proboards.com/index.cgi. All redirects are seamless and will direct you to the correct page you were attempting to access at the old URL.