I've had 3 automatic updates in the last week or so, and i think that it has knocked out my sound. As i use my PC as a jukebox, you can guess that i'm a bit annoyed!
According to the computer properties, i'm missing the 'Microsoft kernal wave audio mixer' but there doesn't seem to be any mention of it on their site. I don't have an XP disc as it was preinstalled by a lovely (grrrr) company that sold me the PC.