Page URL in Sidebar

I have just installed WP 2.1 I can create pages but when I view my blog (http://kimharding.net/blog/) the URL in the sidebar is wrong, i.e. of the “about” page instead of getting /blog/?page_id=2 I get /blog/about/ which doesn’t exist so throws a 404 error if followed. This is happening regardless of theme as they all use php wp_list_pages. Any ideas as to what is going wrong?