As I’ve recently gotten this nice laptop, I’ve found that the light sensor really makes more problems then it solves so I’m shutting it down in both Windows (Fn+A) and in Linux.
Under linux all you need to do is:

echo 0 > /sys/devices/platform/asus-laptop/ls_switch

This fix is valid only for the current session, to persist the settings just install sysfsutils and then in /etc/sysfs.conf put

devices/platform/asus-laptop/ls_switch=0