when i tried to go to forum it just sent me to the game page... try it for yourself if you dont believe me

ED: seems like it fixed itself, o.o .. it may happen again, i have no idea

I had this bug too. It comes and goes. It will probably be fixed soon... hopefully.

I'm having the same problems as well...

if you want to try typing forums in google chrome or whatever, it works and when you try the forum button now, its works again

This most likely happened because the game server messed up a few hours before you posted this thread. Whenever the forums become inaccessible, you get redirected to http://atelier801.com/maintenance, which essentially is the game page without forum buttons.