You need to search
all of your (x)html for links that look like
Code:
<a href="OEBPS/Text/..Text/EndNotes.xhtml">
Somewhere there's a malformed link in your (x)html pointing to something that's not there. It's not in the NCX file you posted, and your OPF file looks fine, so it must be in one of your xhtml files. Use Find and Replace to step through the entire ePub and verify each and every occurrence of "EndNotes.xhtml". One of those occurrences contains something like that first link code I posted.