I'm also facing this issue with the exact same computer (Dell Inspiron 7520). I guess it appears just after adding "acpi_backlight=vendor" to boot options (/etc/default/grub). Unfortunately, this option is the only way to be able to increase or decrease backlight.
-- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg in Ubuntu. https://bugs.launchpad.net/bugs/1272781 Title: Often system freezes To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1272781/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp
