After creating a forum that prevents guests from viewing discussions, when a guest tries to view the forum it is presented a "not allowed" message and a "continue" button. Clicking this button the user is redirected to an error page.
It seems related to the fact that this "continue" button has - action="#" - when it should be moodle's homepage instead of "#".
Different browsers present different error pages but none is able to deal with it in a clean way.
There are some screenshots attached to illustrate the problem.