I have just had a new PC. I can't be bothered to box it back up and return it. I can't get any audio from DVD's in the DVD ROM. It will play audio CD's fine so there's no connections loose. I've also noticed today that I can get audio from .avi files but not from a ripped DVD.
If you've installed codecs and still have issues, your using the latest version of media player and you've cleaned the lens of the dvd player, then I'd consider a call to the shop who supplied your machine.
Thanks for your help Mouse. I received the PC last month after an insurance claim when my last one blew up. I can get them to sort it but it means boxing it all back up and arranging collection etc etc and I can't be arsed for such a small issue. It's just that I expect a new PC to be problem free.
I'd say then, that there is an issue with the drive itself, as the soundcard seems to be working fine. Can you tell us the make and model of your drive?