Update Listing to comply with changes

Has anyone else recieved email from ebay notifying that you have lisiting that do no comply with changes to Ebays policies or security changes? The email says that I have 1 product that either a) needs to be matched with a product in ebays catologue or b) has an invalid product idnetifer. I'm not sure what I have to do. Will ebay remove this listing if I do nothing? Suggestions welcome.