Responsive: 404 Error – why????

Hi all,

I’m trying to create a website for a friend whose husband created a “fake” site, based on her current blog. Every time I try to create a new page, I get a 404 error when I go to it. Yet, when I preview the page before I publish it, everything looks fine. What is going on?? Is this a problem with the way the site has been created or is Responsive damaged? Please help! I’m so confused…

Thanks!