How to fix WP e-Commerce session_start error

Upon update of the WP e-Commerce on A WordPress Website recently, the checkout Page would be blank (no content) upon updating the cart (e.g. removing a product). The following error message was appearing:

PHP Warning: session_start() [function.session-start]: open(/tmp/sess_8620e4df9bc68133182dddf68a76e6db, O_RDWR) failed: Permission denied (13) in /home/youruserid/public_html/wp-content/plugins/wp-e-commerce/wpsc-core/wpsc-constants.php on line 17
It’s likely that the problem is occurring because of the server setup. Unfortunately the Host I was dealing with was very unresponsive so the following few steps fixed the problem:

1. Find the following in the wpsc-constants.php file within the wp-e-commerce -> wpsc-core directory on your Webserver. if ( ( !is_array( $_SESSION ) ) xor ( ! isset( $_SESSION['nzshpcrt_cart'] ) ) xor ( !$_SESSION ) )
// session_start();
2. Comment out the code as above so the lines will look like //if ( ( !is_array( $_SESSION ) ) xor ( ! isset( $_SESSION['nzshpcrt_cart'] ) ) xor ( !$_SESSION ) )
session_start();

The checkout Page should work as expected again.