Alienware M18 - No sound unless i open and close the lid??

Hi,

I received my brand new alienware m18 last week, from first boot up i don't have any sound at all. to get the sound working i have to close the lid and put the laptop into sleep mode.

i can then open the lid, log in and i have sound..... does anyone know how to fix this... i had to sell one of my kidneys to pay for this machine with a gtx 780m sli config....

Thanks in advance

cauffy