In one of the sites I have created, I am using a specific made up 404 page instead of the default one that comes with the server. This 404 page contains an image, and then a block containing text next to it. I then made the url alias for this page "404." Now when I go into the configurations, and set 404 as the 404 error page, it automatically saves it as "node/4." The problem then arises when you go to a page that doesn't exist. If the page is something like www.yrambam.org/nonexistentpage then there is no problem. The page works. But if the page is something like www.yrambam.org/something/nonexistentpage then the page displays without the image, and the formatting of the page becomes all messed up. I am wondering why this happens, and if there is a way to fix it.
This is definitely an error where the HTML of the 404 page is referencing the image via a relative path rather than an absolute path.
Change the HTML of the page to use the image source path '/sites/default/files/pictures/404-error.png'