I just received an email from our host and they\'ve upgraded our PHP to 5.3, unfortunately though, all the scripts have now broken. I traced it down to the function
http://www.php.net/manual/en/intro.mssql.php
"This extension is not available anymore on Windows with PHP 5.3 or later."
Maybe you should look into converting your app to use PDO: http://www.php.net/manual/en/ref.pdo-sqlsrv.php
If you see such a warning, the first place to visit is the PHP documentation.
From http://php.net/manual/en/intro.mssql.php:
Introduction
These functions allow you to access MS SQL Server database.
This extension is not available anymore on Windows with PHP 5.3 or later.
SQLSRV, an alternative driver for MS SQL is available from Microsoft: » http://msdn.microsoft.com/en-us/sqlserver/ff657782.aspx.