WP won't let me preview or save posts. Preview brings up a blank page, and saved drafts just disappear. Also, toggling between 1 column and 2 columns on the new post page has no effect. I can choose 2 columns, but the columns don't appear. I've tried deactivating pluggins one at a time, even repairing the database, but without effect. Do I need to hire a pro to fix this?