Thank you for the very detailed information. Regretfully we could not check your site because the given credentials is not working for us.
Anyways, please edit your page and find the Below Masthead and Above Masthead slider settings. You must deactivate any sliders because what happen is that the slider being assign on the page does not exists. To know more about how the slider were incorporated in the pages, please check this out:
Please let us know how it goes.