I tried going through the drivers in the list.( on the off chance that one of the older versions might work )
When I installed IDT version 6.10.6425.0 ( 19/8/12)
and did a restart. then there was 2 volumes in the volume control. ( volume icon on the bottom right of screen )
One for laptop and one for headphones.
I started to hear sound when i would click on the headphones slider, but then it would stop again.
Anytime i click on the slider the sound comes back for 2 seconds then goes again.
i then reverted back to the driver you suggested.
did a restart.
no sound from laptop. headphones work ok.
icons are back to normal ( i.e the sound icon bottom right of screen )