hi...i just recently got my first mac (15 inch powerbook...really nice!)....I've been trying to move over my files from my pc to my mac and something weird has happened....when i try to play mp3 files with itunes, i can only open a few of them...like out of 1200 songs i can only open 450 songs..when i double click them it opens itunes but nothing comes out and nothing happens...please help..thanks!