help. i save pages, preview, publish. suddenly they go blank as do all revisions

i have no idea at all what could be causing this but its driving me crazy, i’ve just written a long article page twice and lost it both times.

it happens if i write the page in text, tiny mce or using the page builder plugin. i cant go back to my pages using browser history either.

the only clue i have is that i’m also getting the bug where after clicking the publish button the page freezes while trying to publish.

does anyone have any possible ideas?

my site is focallocal.org