If magento is not showing product page properly and displaying 404 page instead there might be possibility of reporting error.

Check your error log file and see if that error is related to reporting then execute following query in the phpMyadmin

INSERT INTO `report_event_types` (`event_type_id`, `event_name`, `customer_login`) VALUES
(1, 'catalog_product_view', 1),
(2, 'sendfriend_product', 1),
(3, 'catalog_product_compare_add_product', 1),
(4, 'checkout_cart_add_product', 1),
(5, 'wishlist_add_product', 1),
(6, 'wishlist_share', 1);