If it was an error in one of your templates, then creating a default style and viewing the site with that, and with the modifications turned off, would have shown the missing editor.
Good point.
So, I disabled all of my plug-ins individually and through Settings >> Options.
I set the Default style to the vB default style.
I cleared all caches. I purged everything in Internet Explorer (I never open the forum in that browser, so it's good for testing changes).
The forum displays in the default style, but the editors still do not appear. Very strange. Thoughts?