https://bbs.archlinux.org – Dell Latitude 6430 with Intel HD 4000 graphics. Same issue; I noticed it starting a couple days ago. If I go slowly, I can alter the brightness with the keys, but yeah, if I go up and then or go too quickly, it wigs out until I kill X. Even the slider in the setting jumps around while the brightness changes.3.7.5-1-ARCH as well on this system. (HowTos)