Yes, I agree, lpSystemName should be always NULL.
The w32-get-true-file-attributes variable should be taken into account.
DFS: http://en.wikipedia.org/wiki/Distributed_File_System_(Microsoft)
No, I did not compile eMacs myself. I would be interested in compiling x64 version, but I hear it is not trivial. Can you dropbox me your version?
Thanks for your help!
On 13/12/12 19:13, Eli Zaretskii wrote:

Date: Thu, 13 Dec 2012 21:05:37 +0200
From: Eli Zaretskii <eliz@gnu.org>
Cc: 12621@debbugs.gnu.org

Sorry, I lost you.  What is a "DFS server", and how does it modify the
meaning of a UNC?  Can you show the full file name being referenced
here?
[...]
Can you show a command that crashes and an equivalent command that
doesn't?

Actually, scratch all that.  I think we should simply always pass NULL
as the first argument of LookupAccountSid.  If you compiled Emacs by
yourself, can you try such a modification there, and see if that
helps?  I'm interested to know not only whether the crashes go away
when you use NULL, but also whether the file owner and group
information is reported correctly.

Thanks.