Custom Fields not showing up in 3.1.1 upgrade

I just upgraded to WP 3.1.1 (auto-upgrade, originally), and it seems to have broken my custom fields in posts / pages.

The page simply goes blank, as if there’s nothing there, below the post content. I need custom fields for my theme, and I consider this a serious issue…

any help?? I looked around on google and saw a couple other people noticing the same issue, but no one seemed to know what the problem was?