For reasons I'm not able to determine, after using a media player, and closing it, it also seems to turn off my sound card, a Creative SB X-FI. I also had a older Creative card in here which did the same thing, though I no longer have it or remember what specific model it was. This same thing happens on another PC of mine, and I'm wondering if it's related to Winamp, my main media player. Though it also happens with Media Player Classic, after using it or even trying to open the volume menu during it's use. It does not happen if I immediately open the volume window and keep it open the entire time I'm using the computer. I don't believe this is related to any hardware specifically, since I can do it on both of my computers, whatever sound device is used. The other computer uses the internal soundcard on the motherboard, and it still stops running after using a media player.
When it has closed, the only sound output I can get is from the media players, nothing from online sources like youtube and the like will work.
Currently running XP Home SP2, pentium 4 processor, the sound card in this computer currently is a Creative SB X-FI. I'm not sure what my motherboard is, the listed specs just say Intel. I've updated all sound devices to the latest version, newer or older seem to have no impact.