files are in the "set number" mod package? If you have Column Grid installed, this mod most likely needs to alter one or more of the same files, which would cause problems.

These are the files I added:
2 files in extra functions(set_num_products & set_num_product_dd) and lang/english/template/set_num_products, and of course the modifications to modules/template/product_listing and templates/mytemplate/template/tple_modules_product_listing.

I took off set_num_products under functions/extra functions and the website comes up and the addon is working for now. Not sure if this is a good fix or will problems arise after disabling the one file.