Page automatically goes to 404

For some reason, ny pages have just started going to the 404 page.

I have no idea why this would happen.

If I create a new one and preview it before saving, it shows up fine, but as soon as I save it and cliuck to view it from either admin or the actual site, it goes to the 404 error page.

You can see it by clicking one of the top links on my site:
http://glastonbury.ws

Any ideas are appreciated, as this is a weird one.