Error 500 - Can't delete products after adding numinix product fields addon

Hi, I've came across a problem, Ive identifed where it is (Wild guess maybe) , but not sure how to fix it,

I needed to add numinix product fields onto 1.39D so i could getthe EAN numbers onto admin,

After a few attempts, I got it to work in conjuction with CEON mapping (Merging),

It wasn't until i wanted to delete some products i notice they won't go!

a few people replicated it for me, and they got a blank page instead of it deleting the product and returning to admin,

Something strange is also happening, when i add a product it will not show up in the category, But it will in "New products"

The answer is somewhere in as far as i can make out , functions/general.php

This is the error i see , but the people that replicated it don't, they just see a blank page

Server error
The website encountered an error while retrieving http://********//product.php?action=delete_product_confirm&product_type=1&cPath=39_224&page=1. It may be down for maintenance or configured incorrectly.
Here are some suggestions:
Reload this web page later.
HTTP Error 500 (Internal Server Error): An unexpected condition was encountered while the server was attempting to fulfil the request.