I've always run my WordPress sites with a static front page and the posts page on a separate, blank page. So, a static frontpage at http://www.jpehs.co.uk/ and a posts page at http://www.jpehs.co.uk/blog/. This has all worked fine until a couple of weeks ago, when the posts page -- and the pages listing archives (e.g. http://www.jpehs.co.uk/2011/10/) and post categories (e.g. http://www.jpehs.co.uk/category/conferences/) started turning up nothing but a copyright notice for the theme. This seems to happen no matter what theme I've got installed.
Has anyone any idea why this might have suddenly started to happen, and what I can do to put it right?