Unable to load the requested file error

[eluser]pzntec[/eluser]
Hello!

I have the following code in my controller:

Code:

$this->parser->parse(base_url().'themes/default/index.php', $data);

And getting error:

Unable to load the requested file: http://localhost/PB_MVC/themes/default/index.php

However, when I type in the same url into the address bar, the page loads fine.

I can't for the life of me figure out what's going on.

Thanks in advance!

ADDITIONAL INFO:

Configs & Helpers are set as:

Code:

//Commented lines I've tried.
//$config['base_url'] = '';
//$config['base_url'] = 'http://localhost';
//$config['base_url'] = 'http://localhost/';
//$config['base_url'] = 'http://localhost/PB_MVC';
$config['base_url'] = 'http://localhost/PB_MVC/';
$autoload['helper'] = array('url');

My folder structure is:
-PB_MVC
--application
--system
--themes
---default