I’ve encountered this on more than one occasion. I’m dealing with it as I type this. It is an Compaq Presario 2100 laptop. The client reports prior to losing sound he was doing Windows Update. This just struck me but often times Windows Updates will try to install “newer” drivers for the computer. I wonder if this has anything to do with it. I’m trying to install the latest driver available from the HP website. I’ll report back with my success or failure.