Page 404 is always a hole into a blackbox which hides the deepest depths of the websites from search engine indexation robots. Or maybe you've got there because we changed the content management system or so? You'll never know if there was something there or the 404 page just means you have no access - masked as an absence of a page. HTTP status codes from 400 to 500 are used to designate client errors. Someone have sent you a wrong link and see - you're standing and waiting with a bouquet on the corner - but at the completely wrong neighourhood. Four hundred and four is the most mundane failure of all the failures, the error you don't look at more than a second. So this is just an er ro r or po em.