music files dont sound good
 

after downloading music files i go to play them and they all have "skips" or "loud sharp pitchs" now i have used others programs like winMx/ audiogalaxy and others and i have never got these sounds before...and i can't got over that every file has the same problem..the problem continues even when i play the file on realplayer or musicmatch all in the same spots so i know the problem is in the file... why is this happening ... thank you
the muscle men