That happened to me a few months after I got my computer, Sprig. For me, it was driver incompatibility. Windows XP didn't like the driver that Toshiba had for my sound card. So there was an updated one that I had to download, and it suddenly started working again.
But it sounds to me that you've already tried that, so I'm probably no help.
My frustration is still in my wireless card. When I bought it, the installation guide said that even though a message would come up during installation that it didn't work with XP, it really did, so go ahead. (Certification or some such issue.) So I did, and now my laptop will never go into hibernation mode--or if it tries, it freezes. EVERY TIME. It drives me crazy. I've gone to the Netgear site to download a new driver, but there is no new driver. It's the exact same version I bought the card with. And calling the company won't help; they charge you to speak with a person, even for customer complaints like this. It's ridiculous. So the only thing I could do to solve the problem, I think, is to get a new wireless card.