Vista - No Sound or Applications in Mixer

I've had this issue for quite a while. i've installed sound driver after
sound driver and I still can't get sound. When I open the mixer, I don't see
the default "Windows Sound" or any of the applications that are open. Also,
when I try to play an MP3 in Winamp I get this error message, "Bad
DirectSound driver. please install proper drivers or select another device
in configuration. Error code: 8007005"

I've been researching this a whole lot and tend to think that it's a
permissions issue somewhere. Has anone fixed this issue?

BTW - I'm running Vista Ultimate on a Compaq nx9420 with 2 gigs of Ram. I
have all the latests service packs and updates installed.

PLEASE!! Someone help me!

Thanks
Scott