On the login page (login/index.php), when the 'standardold' theme is selected, the following error is thrown
Coding error detected, it must be fixed by a programmer: Trying to reference an unknown block region side-pre
On checking the config.php for that theme we see:
'login' => array(
'file' => 'general.php',
'regions' => array(),
'options' => array('langmenu'=>true),
I no next to nothing about Moodle 2 themes but it would seem that either is Moodle is looking for that region when it shouldn't or that it should actually be defined in the 'regions' array.