The appending of /customers/ is probably coming from the menu. PhpDig doesn't know that when it sees <a href="/customers/" ...> you really mean it to be <a href="http://www.ascential.com/customers/" ...> so PhpDig treats it as a subdirectory of the current page, whatever that page may be. To tell PhpDig to treat relative links as if they were coming from a different place, and not the currect page, try sticking a base href tag in the head portion of the HTML. Note though that this will treat all relative links as if they were coming from whatever link is provided in the base href tag.
HTML Code:
<base href="http://www.ascential.com/" />
<!-- or -->
<base href="http://www.ascential.com/dir1/" />
<!-- or -->
<base href="http://www.ascential.com/dir1/dir2/" />