I'm having similar bother with XP I kept geting error messages and had to disable the sound card as the machine got to the point where it wouldnt boot. I've put a new sound card in, it boots fine emails ok surfs ok but but theres still nowt to listen to, there must be be a less invasive way of sorting things out rather than clearing the hard drive.
I've made sure that all my updates are the latest but I have come across situations where the latet version of an update has stopped an application from working!!!