NEC 2500A HELP Please!

I just installed the new drive and it plays audio CD’s great. I can hear music from it. However when I put a DVD in the drive, I can see the video but I am not getting any audio. Why can I hear CD’s playing but not DVD’s?

I had the same problem two days ago, after re-installing XP. I unistalled the sound drivers fom the device manager in the Control Panel and uninstalled my DVD software, PowerDVD XP. I then rebooted my PC, re-installed Creative sound driver and PowerDVD XP. I now have sound on my DVDs.