Can't edit existing posts or create new ones

I’d starting having problems using Firefox over the last week to edit an existing post or start a new one. Now it’s happening in Chrome. A friend logged in from their computer, same deal.

I load up the edit post. I can see the title. The Add Media button. the Tab for visual and for text. There are no buttons in the Visual tab, there are in the Text tab, but (for an existing post) no text shows up in the post editor box. I can’t click in to start a new post, either. It’ll show the proper word count for an existing post and show when it was last updated. That is all I have.

I don’t know why this suddenly got worse today, I didn’t do anything to the site. No changes, no updates, nothing. The dashboard is also agonizingly slow to load, for everything. I activated the standard theme, that didn’t do anything. I deactivated some plugins, one by one, that didn’t change anything.