I had this same issue and same solution. I believe it was caused by using etckeeper to restore files in /etc (including /etc/passwd and /etc/shadow).
-- You received this bug notification because you are a member of Desktop Packages, which is subscribed to gnome-screensaver in Ubuntu. https://bugs.launchpad.net/bugs/45368 Title: Unable to unlock screen (Dapper) Status in “gnome-screensaver” package in Ubuntu: Invalid Bug description: Binary package hint: gnome-screensaver gnome-screensaver refuses to accept the user password, though the regular login process works fine. Need to restart X to get around the problem. Changing the password does not help. In constrast, when logged in as the root user, it is not possible to lock the screen - the password dialog is bypassed altogether allowing anyone to use the account. Found the following in /var/log/auth.log (when logged in as a regular user): May 16 21:42:35 localhost unix_chkpwd[15122]: check pass; user unknown May 16 21:42:35 localhost gnome-screensaver-dialog: (pam_unix) authentication failure; logname= uid=1000 euid=1000 tty=:0.0 ruser= rhost= user=gille May 16 21:42:36 localhost gnome-screensaver-dialog: (pam_unix) authentication failure; logname= uid=1000 euid=1000 tty=:0.0 ruser= rhost= user=root In other words, unix_chkpwd does not recognize my user name for some odd reason (in spite of both user name and user id being correct in the above lines), or so it appears. Xscreensaver has the same problem. Not sure if it is relevant, but the /etc/pam.d/gnome-screensaver file includes common-auth which in turn contains the following: auth required pam_unix.so nullok_secure I am able to reproduce the bug every time. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gnome-screensaver/+bug/45368/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp
