Dear lizP,
The notices you have posted are harmless.
Yes, there definitely can be an issue related to low memory or no execution time available. Please increase the available memory as described here: http://codex.wordpress.org/Editing_wp-config.php#Increasing_memory_allocated_to_PHP I would suggest starting with at least 128MB, as 78000 items is quite a lot.
Please let me know if you are satisfied with my answer and if I can help you with any other questions you might have.
Regards,
Paweł