Seems to be a duplicate bug of https://bugs.launchpad.net/ubuntu/+source/kdebase/+bug/181343 where a fix (http://ati.cchtml.com/show_bug.cgi?id=992#c26) is posted, included here for quickness:
In /etc/ati/authatieventsd.sh locate XDM_AUTH_MASK variable and ensure it is set as: XDM_AUTH_MASK=/var/run/xauth/A$1* -- KDM hangs upon logout in Kubuntu 8.04 https://bugs.launchpad.net/bugs/211318 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs