This may just be the cache headers. Most sites have caching that tells browsers either "never cache this site" or "cache for a short time, but after that you must fetch a fresh version and can't use the cached version." HN's say "always try to fetch a fresh version, but if that fails, it's fine to show the user the cached version." So if your connection is actually down (vs. just slow), your browser's old cache of HN may still display, unlike most other sites.