With Simple:Press activated, when I log out of wordpress from the admin bar I get directed to 404 page not found. The link it is trying to direct me too does not exist but oddly is mysite/forum-2. I think forum-2 was the original page set up by Simple:Press on install but not sure if that is relevant.

De-activating the Simple:Press plugin returns everything to normal and logging out takes you to the log in screen as expected.

 EDIT: Solved – only just got to the setting for login/registration re-directs