hi,
it's an oldie release of modx apparently (just type /manager... after the domain name)
it looks like an url rewriting issue because
1 - when you type /manager no 404 err behind, you see the manager login page
2 - when you follow an internal link the 404 page is the server one
3 - if you try /index.php?id=10 for example (or whatever id except for 1) you get a 404 error too but, this time you personal one (the one you've set in modx)
it seems like you're hosted on a windows machine (how do i know ? when you follow the
http://www.encapdrugdelivery.com/library link, as windows system is not case sensitive, instead of the 404 page you fetch
http://www.encapdrugdelivery.com/Library/ directory with its file list, very windows like... and not that secure by the way) that may explain problems with the url-rewriting...
have swing