No sound!!! Integrated sound on motherboard

I just built a computer and fired it up. Everything works but the sound. The operating system is Windows 2000. I tried it with Windows 98 as well to no avail. I’ve updated the Bios,CMOS, Chipset, Motherboard drivers…everything I could think of. Still now sound. I notice there is a conflict in device manager on “unknown device” under “sound, video and game controllers”. I have tried to remove all devices from there and restart the computer. Nothing. I disabled the onboard sound in CMOS and installed a new PCI sound card (Mad Dog) and still no sound. Under sounds and multimedia properties, Sound volume controller is ghost out. Under Audio tab, it says No Playback Devices. My mobo is shuttle AB60N v1.2. Please help. Thanks in advance.