CodeIgniter 2.1.2 and MS SQL on PHP 5.3.13 - sql-server

Question

I have been at this one all night and our offices open in 69 minutes.
Our server was just updated to PHP 5.3.13 and a critical online application that connects to MS SQL 2008 is just producing a blank page - no errors being logged, just snow. It is written in CodeIgniter 2.1.2.
If I do not autoload ( or try to connect to the db ), the page displays the static elements. Once I add the database.php config file, it's a white-out.
I am trying the mssql and the sqldrv drivers and getting the same results.
I am hoping to find some ideas on how I can go about debugging this solution in an ASAP sort-of-way.
My offending config (which worked until the upgrade) in the database.php looks like this:
<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
$active_group = "default";
$active_record = TRUE;
$db['default']['hostname'] = "<<SQL SRV NAME>>";
$db['default']['username'] = "<<USERNAME>>";
$db['default']['password'] = "<<PASSWORD>>";
$db['default']['database'] = "<<DATABASE NAME>>";
$db['default']['dbdriver'] = "mssql";
$db['default']['dbprefix'] = "";
$db['default']['pconnect'] = FALSE;
$db['default']['db_debug'] = TRUE;
$db['default']['cache_on'] = FALSE;
$db['default']['cachedir'] = "";
$db['default']['char_set'] = "utf8";
$db['default']['dbcollat'] = "utf8_general_ci";
ANY thoughts are GREATLY appreciated.

Answer 1

A bit late now I suspect, but the current version of CodeIgniter (2.1.2) has the following in its Database config file by default:
$db['default']['hostname'] = 'localhost';
$db['default']['username'] = 'username';
$db['default']['password'] = 'password';
$db['default']['database'] = 'database';
$db['default']['dbdriver'] = 'mssql';
$db['default']['dbprefix'] = '';
$db['default']['pconnect'] = TRUE;
$db['default']['db_debug'] = TRUE;
$db['default']['cache_on'] = FALSE;
$db['default']['cachedir'] = '';
$db['default']['char_set'] = 'utf8';
$db['default']['dbcollat'] = 'utf8_general_ci';
$db['default']['swap_pre'] = '';
$db['default']['autoinit'] = TRUE;
$db['default']['stricton'] = FALSE;
Note the extra couple of configs there at the end. It may be looking for them but as they're not supplied it's erroring...