Comment 1 for bug 662760

Hi, thanks for your bug report. I cannot immediately understand why this is happening. When I try the same thing it does not happen. Could you try the following and report the output?
  $ # connect external monitor
  $ disper -v -S
  $ disper -p
  $ # disconnect external monitor (make sure your terminal has focus)
  $ disper -v -s
  $ disper -p
If doesn't trigger the bug the problem is in auto-disper, if it does please report and attach the file created by nvidia-bug-report.sh (which is included by the Ubuntu package nvidia-glx-*; or else include /var/log/Xorg.0.log and dmesg) since it may be a driver-related problem.