Before I installed Magic SEO if a page wasn't found the user was sent to my custom 404 page. Now if a page is not found they see a page of HTML code. Obviously this is not a good customer experience. It could happen if a customer follows a link to a product that no longer exists. My site has lots of inbound links to old products.
How can I make it so that when an old link is requested the user sees our 404 page rather than a junk page like they do at this example: http://www.make-me-beautiful.co.uk/shop/product_info.php?products_id=9