Upon further investigation, I've found that on my system the issue was related to:
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=667470 Removing libpam-systemd successfully worked-around issue. -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
