Naming items with WordPress can cause some unusual problems when more than one item has the same slug/name.
After you create a custom post type, go to the Settings > Permalinks screen and save your permalinks again. That will flush out the permalink cache. Until that step happens, generally every instance of the custom post type will turn up a not found error.
I would also give the page where you query for the custom post type a different name/slug from the custom post type. That will help cut down on any errors there.