I updated my sound driver, and the sound no longer works. Even worse, the "roll back to previous driver" does not work! The driver is Conexant High Definiton audio. Any help?

Uninstall anything that's left of the original, if possible use a clean up tool avaliable as a separate download from their website, that will usually solve issues caused by files missed by the standard uninstall programs.

Then attempt to re-install the latest drivers. If that doesn't work then try installing an earlier version of the existing drivers.

Well, I got owned by M$ update. Just formatted my PC and went back to XP.

Quote from h3adbang3r :

Well, I got owned by M$ update. Just formatted my PC and went back to XP.

Any BSOD screens? There is a bug going around in Vista, from memory 0x00000124 or very close to that has this effect, sound drops from anything really (example: fullscreened game, windows media player)

The problem is it crosses over many types of hardware. nvidia & ati also onboard and pci sound cards