Earlier today we have been beta testing with new forum software, currently we are back to the old forums. However if you happend to have logged into the beta setup earlier today, chances are that your browser might have cached a thing or two. This can result in you not being able to access the forums. The solution is very simple, please clear your browser cache and cookies and you will have solved that issue (that a few have exerienced).
Apologies for any inconvience caused.
