The problem appears to be due to xfsettingsd (part of Xfce4)
https://bugs.launchpad.net/ubuntu/+source/nvidia-graphics-drivers-331/+bug/1308105
The problem appears to be due to xfsettingsd (part of Xfce4)
https:/ /bugs.launchpad .net/ubuntu/ +source/ nvidia- graphics- drivers- 331/+bug/ 1308105