in access_control/resources.php you may get a "Call-time pass-by-reference has been deprecated" warning message when running on php5. Apparently passing by reference is deprecated so you either alter your php.ini file or make the following change. Granted much of the code is built on php4, so I don't know if or how you'll choose to handle this.
while($obj->getTreeNext($tree)):
// See if this resource is locked
$query = $this->access_control_model->fetch('resources','locked',NULL,array('id'=>$tree['row']['id']));
$row = $query->row();
// Get Offset
$offset = $this->access_control_model->buildPrettyOffset(& $obj,$tree);
//in above line if you change it to:
$offset = $this->access_control_model->buildPrettyOffset($obj,$tree);
