Whenever I Try To Play A song either on limewire or napster free. it plays in slow motion or it crackles HELP

No matter wut... on any song.. it starts out good... but 2 secs into the song... it makes a crackle.... then goes into slow motion... its very annoying... even when i start up the camputer and it plays the du nu nu nu na na..... it crackles on that... and it takes like 30 seconds more then it should take... thx