had another one in the past hour or so
when i came back, i was logged out
and every time i log in, i'm still logged out in the top of the screen
but if i click on anyting that i am able to click when i've logged in as before, it's all there
i'm just not shown as being logged in on the main page

no screen shots as it's just the same as before

 

i had the same thing - presumed the forum was offline for cleanup / maintenance.