Rohit
Xref.nb does exist. I created it using the file menu
All I did to get
XRef = NotebookOpen[FileNameJoin[{Directory[], "XRef.nb"}], Visible -> False]
Was take your example
X2382901 = NotebookOpen[FileNameJoin[{Directory[], "X2382901.nb"}], Visible -> False];
And replace X2382901 by Xref and replace X2382901.nb by Xref.nb
So I'm assuming that
FileNameJoin[{Directory[], "XRef.nb"}]
exists
Once again, thanks for your patience with me.