BTW, I can create the page – but in this specific instance, when I add it to the tabbed Navigation Links at the top of the page and click on the tab, it takes to me a URL for a page I trashed. And to make it just a little more weird, before clicking, when the cursor hovers over the tab, the correct URL is shown. So it looks like everything is fine except when I click on the tab and end up on a 404 page.