Could not find valid configuration directory, while adding an image to an event.

While creating an Event, in editor if we click plugin for "Image Icon" or "Link Icon" to add an image or a link, this pops up with the following error.

"Could not find valid configuration dir best guess: /var/www/drupal.civicrm.org/public/sites/drupal6.demo.civicrm.org/modules/civicrm/../../sites

If this is a standalone installation (i.e. not a Drupal or Joomla module) and you'd like to re-initialize it, click here."

Tested in Civicrm Demo site also.