@photocrati – Yes the problem did continue when I chose WordPress Twenty Fourteen as the default theme.
I then did a manual reinstall of WordPress, replacing the wp-admin and wp-includes directories (with plug-ins disabled).
Many issues have been resolved as a result of the reinstallation, but not the NextGen gallery problem. I reinstalled the basic NextGen gallery and still get the Exception thrown Error Message.
Looking forward to your reply. Thank you.
Terry Rich