I am running Xubuntu 12.04 AMD64 LTS on a ThinkPad Edge E325. The hardware volume keys did not control the internal duplex stereo but were mapped to HDMI. This can be checked by right clicking Sound settings in system tray, (only works under Xubuntu DE.) You should have two volume entries under Output Devices. Hitting the hardware volume keys should control the HDMI output (as opposed to Analogue Stereo.)
look in Settings / Settings Editor (not the normal Settings Manager.)
xfce4-mixer, there is the setting
/active-card which had the value:
Select the ‘active-card’, and hit the ‘Reset Property’ button. This may turn the setting into:
If it deletes field completely you will need to recreate:
I had a problem where Value would keep resetting to, ”HDAudioGenericAlsamixer” no matter how many times I repopulated the Value field. If you find this to be true then kill “xfce4-volumed” process within Task Manager before reattempting.