CodeIgniter problem after upload to hosting

Base URL should be absolute, including the protocol:
$config['base_url'] = "http://somesite.com/somedir/";
If using the URL helper, then base_url() will output the above string.

Passing arguments to base_url() or site_url() will result in the following (assuming $config['index_page'] = "index.php";:

echo base_url('assets/stylesheet.css'); // http://somesite.com/somedir/assets/stylesheet.css
echo site_url('mycontroller/mymethod'); // http://somesite.com/somedir/index.php/my...r/mymethod