I got this error today after installing the current ckeditor on 1.5.1 and setting my default editor (Configuration -> My Store) by setting "HTML Editor" to ckeditor.
I had already defined DIR_WS_EDITORS in my configure.php
The false error is caused by admin/includes/header.php line 95:
Code:
if (HTML_EDITOR_PREFERENCE != 'NONE' && !is_dir(DIR_FS_CATALOG . 'editors')) {
I made my problem disappear by changing that code to:
Code:
if (HTML_EDITOR_PREFERENCE != 'NONE' && !is_dir(DIR_FS_CATALOG . DIR_WS_EDITORS)) {