CI_Controller error

[eluser]Unknown[/eluser]
Fairly new to CodeIgniter, but am getting a weird problem and hoping the community can help me solve the issue.

I have a controller 'Currency' that is failing to instantiate with a base constructor.

Code:

class Currency extends REST_Controller
{

function __construct()
{
  parent::__construct();

}
}

so tracing through the parent constructor all the way back to the matriarch CI_Controller
everything is peachy keen until it seems to fail on this line:

Code:

$this->load->set_base_classes()->ci_autoloader();

In the CI_Controller __constructor....
Anyone have any idea why that might be happening?