No sound in G40 but external head set plays sound

[madmaven]

I have a G40 with no sound from the speakers. I have installed the IBm software installer and gotten all the latest drivers, Running XP Pro w/SP2. Everything checks out in the Device manager, and in the control Panel also. When I hook up a head set the sound is perfect. I have checked every setting I can think of. I looked in the bios found nothing. except the hertz is 220 which I can change but know nothing about this so didn't. Any suggestions?
I did just purchase this from a reputable distributor so he will take it back but would like a fix because I would like to save the shipping and time involved.
thanks for any help.

MM