Alex Sherman

Actually I had this on Apache on Ubuntu system (installed as Zend Server Ce PHP 5.3)

I had the same issue, afer debugging with firebug and crossing it with Apache logs, I found out that the plaugin was requesting the JS files using the HTTPS protocol prefix. After a short investiagtion, I found that in file ckeditor_class.php in line 30 there was:

if($_SERVER['HTTPS']) {
  $siteurl = str_replace('http:', 'https:', $siteurl);
  $this->plugin_path = str_replace('http:', 'https:', $this->plugin_path);
}

Apparentaly my server configuaration was producong

$_SERVER['HTTPS']='off'

The following fix should be applied to the plugin code, using a core wordpress function to check the required protocol:

if(is_ssl()) {
  $siteurl = str_replace('http:', 'https:', $siteurl);
  $this->plugin_path = str_replace('http:', 'https:', $this->plugin_path);
}