I have an HP Pavilion, and for some reason it has been making a crackling noise with the sound that comes out. This happens only when I play a CD, or a DVD. It isn't the speakers because I tried my headphones and it made the crackling noise through those. If I listen to music that's already on my computer, I do not get a crackling noise. It is a DVD CD-R/W combo drive. Maybe it needs cleaning?