Using my normal browser (Firefox 20.0.1), I can go to forums.adobe.com but can only read messages -- I'm not logged in. If I click on "Sign In" (upper right) and then enter my e-mail address and password, the site goes into an infinite loop of page redirection, which only stops when I hit ESC or close the browser.
The only workaround I've discovered is to login using Internet Explorer.
Clearing the browser cache also works because FF is very persistent in keeping all browser cache even if they are corrupt. Clearing them manually ensures a fresh page is downloaded to start your browsing adventure.