I'm having the same problem. I can go into the sound configuration thing and test out each of my speakers, and they produce sound just fine. I plug my speakers into my ipod and everything works correctly. However, i still have no sound from videos, music, or internet/messaging systems. I think dwoodbury and i are having the same problems.
The only changes i've made recently involve transfering a TON of data from an IDE drive to my new SATA computer. No software installation occurred in between the two situations (sound then no sound).
EDIT: Nevermind. I don't know how, but the audio driver must have become corrupted or something. After a couple of uninstall/reinstall cycles, i finally got the sound to work.
dwoodbury, try this site http://www.free-codecs.com/Realtek_HD_Audi...cs_download.htm
That's where i got the codec that finally worked.
Edited by Heretic Monkey, 04 December 2008 - 09:56 PM.