Trying to fix something else (sound problems), I ended up partially (almost completely) fixing this bug. The two problems I had disappeared: when I press Fn+up the keyboard does not lock, and volume is not changed. (What still feels buggy is that, when changing brightness levels, I get a very short flash of the screen in a different brightness setting, and then it goes to the appropriate level. OSD works fine, though.)
What seemed to fix this was following a HOWTO for reconfiguring PulseAudio: http://ubuntuforums.org/showthread.php?t=789578. Could there be any relation? I'm not good enough in Ubuntu to diagnose that by myself, but I'm definitely willing to help if anyone wants to tell me what to do / look for.
Trying to fix something else (sound problems), I ended up partially (almost completely) fixing this bug. The two problems I had disappeared: when I press Fn+up the keyboard does not lock, and volume is not changed. (What still feels buggy is that, when changing brightness levels, I get a very short flash of the screen in a different brightness setting, and then it goes to the appropriate level. OSD works fine, though.)
What seemed to fix this was following a HOWTO for reconfiguring PulseAudio: http:// ubuntuforums. org/showthread. php?t=789578. Could there be any relation? I'm not good enough in Ubuntu to diagnose that by myself, but I'm definitely willing to help if anyone wants to tell me what to do / look for.