I tried out the DVD player of my powerbook (1.25 Ghz, 512 RAM) for the first time by watching LOTR: Two Towers. In certain scenes (not just fast paced action scenes), lines appear in the middle of the screen. Is this normal? Or is there something wrong with my powerbook or dvd? I don't have a dvd player so I can't test out whether it's just the dvd. thanks