Hi Guys,
A temporary fix.

Download and install Spark (or any other keyboard shortcut app).

http://www.shadowlab.org/Software/spark.php


Then create a applescript shortcut mapped to something like Option, fn and Volume up key(F12) (or anything you like)

Now use the apple script for volume up of:

-- volume up
set current_volume to output volume of (get volume settings)

if current_volume is less than 100 then
set current_volume to current_volume + 2
end if

set volume output volume current_volume



This sets the volume to increase by a little each time you press the buttons.
This can be changed by making + 2 larger for larger steps and smaller for smaller steps.
Repeat for decrease volume using


-- volume down
set current_volume to output volume of (get volume settings)

if current_volume is less than 100 then
set current_volume to current_volume - 2
end if

set volume output volume current_volume



Hope this works for you too.
If it does not work, you may need to go to System preferences>Keyboard>Mission Control
and then untick Show Desktop (F11) and Show Dashboard (F12).

Regards