Problem: Your PHP max execution time was exceeded and PHP quits.
Solution: Extend PHP's Runtime Configuration max_execution_time.
For security reasons try changing max_execution_time to 60 seconds first, then longer if you need it.
* Also, you'll need to change the pathing I've used as appropriate for you site / system.
# Drupal Solution Details #
First we need to play, "Where's php.ini?"