Hi Peter,
Typically you’ll see the white screen in WordPress when there are either errors in the code or not enough memory on the server. Have you tried turning WordPress debugging on to see if there are any errors (http://codex.wordpress.org/Editing_wp-config.php#Debug)? Have you tried increasing the amount of memory on your server?
If you provide me FTP and WP admin access to your site I can take a look – just email to jonahcoyote [at] gmail [dot] com
FYI, I work for Modern Tribe and am filling in for Rob while he’s away.
Regards,
Jonah