I also got this error and encountered a .htaccess in my http-root. This file restricted any webuser. I did not
create this file by myself and I did not
alter any config file of the apache2. It simply occurs from one second to another. So I guessed there was an attack.
I renamed the file (something like htaccess_old). After that, the error was gone.
I was able to reproduce this error and it reveals, that the installation process of a php-mysql-based site seems to create this file.
I installed that software before and never had any problems like this. But i changed the owner of the webroot fromm wwwrun to root again and the problem was gone.
Yes, i know, you shouldn't give the wwwrun access to the webroot-directory anyway. But it's still weired, that this htaccess-thing occours spontaneously (or so it seems).
Hope someone will find this useful