I've been using WP as a CMS for my client's site, betterdaysleep.com, for some time now. They recently decided to add a blog, so I created a page titled "blog" at betterdaysleep.com/blog, and told WP to list the posts there (under Reading Settings). However, I ran out of time that day and deleted the page so that no one would stumble across it before I got it fully set up.
Now, when I create the page again, I get my 404 page when I visit it. The page title is correct, but the page content won't show up. Only if I change the page slug to something different will it work. I've tried this will some pages that I had quite a while ago, and as far as I can tell, once a slug has been used once, it can never be used again, even if the page has been deleted.
Any ideas? If only I'd never deleted the page in the first place!