strange crackling sound apperaing on some of my samples

i've been sampling straight out of my itunes library recently, and for the most part, its been working well. However, sometimes, some of my samples will suddenly have a weird crackling sound on them out of nowhere. when i first sample them, they sound clear. but some of them just get this weird sound out of nowhere. its not like a record player crackling, but a little more electronic sounding. anyone know why this could be happening? thanks

im about to eat some crackling pork.

(other than that - no input)

Could you describe said "crackling"

back from dinner - had a think about it - its probably comething to do with the cable connection between pc and mpc or volume? thats the best i can think of (or maybe alot is going on in ur computer and causing the sound...maybe shut ALL programs except itunes or maybe record using a program other than itunes and see if it still happens)

yeah, i was thinking it might have something to do with the cables, but i was wondering why the sounds didnt have the crackle when i first sampled them and used them....but when i would later go to them, they would all of a sudden have this crackle. im gonna burn the songs i sampled onto a CD and then sample them from my CD player and see if the problem persists. thanks for the input