I don't have any idea what happened but the sound just stopped working, I have a Dell computer with windows XP. The video card is built in to the mother board but I don't think anything is wrong with the hardware. When I try to play a song in realplayer it says that another program is using the audio software and hardware but I can't find anything using it or stopping it from working, I have checked all the drivers and there are no conflicts. Please help if you know what to check. I'm out of ideas.