This bug seems to be related to a kernel problem. Fedora is dealing with the problem as well.
Have a look at these two bug reports: https://bugzilla.redhat.com/show_bug.cgi?id=1067071 and https://bugzilla.redhat.com/show_bug.cgi?id=1093991 ** Also affects: linux Importance: Undecided Status: New ** Bug watch added: Red Hat Bugzilla #1067071 https://bugzilla.redhat.com/show_bug.cgi?id=1067071 ** Bug watch added: Red Hat Bugzilla #1093991 https://bugzilla.redhat.com/show_bug.cgi?id=1093991 -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to xorg in Ubuntu. https://bugs.launchpad.net/bugs/1307877 Title: Laptop Monitor Brightness reduced to minimum and disabled after disconnection from external monitor. Status in The Linux Kernel: New Status in “xorg” package in Ubuntu: Confirmed Bug description: Hi, I have the following problem under Ubuntu 14.04. As soon as I disconnect my external monitor from my Laptop (Lenovo X1 Carbon), the brigthness is reduced to minimum (backlight switches off) and I can not increase it again. When I use the brightness control keys the brightness bar shows that it is set to maximum even though it clearly is not. Using the control keys still changes the brightness bar but does nothing to the brightness itself. Upon a restart of the laptop the brightness returns to its maximum and is controllable again. I encountered this problem under the Unity version shipped with Ubuntu 14.04, but it might happen with other desktop managers as well. This problem did not exist when my Laptop was running under Ubuntu 13.10. To manage notifications about this bug go to: https://bugs.launchpad.net/linux/+bug/1307877/+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
