I have a Ubuntu 13.04 installation (with xubuntu-desktop installed if that matters). My problem is that sometimes the sound hotkeys (Fn + F10 / F11 /F12) just stop working (I can still change the sound volume from the sound applet).
I've tried running
xev - it looks like the system just ignores these hotkeys (nothing is shown in the output).
Not sure if this is a related problem, but when the system boots, the sound level is always set to maximum as soon as, e.g., screen brightness level is remembered and restored correctly.
P.S. My hardware is eeePC 1005HA. The system is not a clean installation, it's being upgraded since 9.10.