Changed my my passwords.
Added a secret key.
I’ve totally reinstalled a new clean version of WordPress. That didn’t fix it.
I’ve recreated the db in a diff location and pointed the config over there. That didn’t fix it.
I’ve disabled and deleted all the plug-ins. Didn’t fix it.
I’ve disabled and deleted all the old themes, except for the one that came with the fresh install of WordPress. Didn’t fix it.
I’ve looked at the .htaccess files. They look like they’re supposed to.