Recently, and on another occasion a while ago, my website was experiencing the White Screen of Death (WSOD).
According to http://drupal.forhumanists.org/book/white-screen-death you need to check for possible PHP errors that are occurring.
To see the errors place the following into
index.php (located in the site root folder):
error_reporting(E_ALL); ini_set('display_errors', TRUE); ini_set('display_startup_errors', TRUE);
My site then showed the following error:
Fatal error: Allowed memory size of 134217728 bytes exhausted (tried to allocate 7642683 bytes) in /home4/rinetcom/public_html/glenneaton/includes/menu.inc on line 968
settings.phpfile on your server from "444" to "777"; otherwise you will not be able to over-write it with the newly saved file you have on your computer.
settings.phpfile permissions to 444, or 555.
Retest your site and if desired remove the error reporting code entered into