I am having the same problem.
one user gets sound and the main user doesnt :x
i have checked all the settings that I know of in the control panel and cant find any problems there
one thing that i thought may have been a problem was i installed a demo version of NERO 7 and when it expired it wouldny let me use it (obvously) but also when I treid to run different media items the Nero box would come up and ask for the rego and therefor I couldnt get the item to play.
I treid to uninstall Nero but it didnt exist in the programs list and so in the end I just deleted all the files in the Nero folder. This maybe completly unrelated but i thought I had better mention it :idea: