inspector

Hi i`m new here but could you please help, im running windows xp home edition, i can play music through my computer but when i try and watch a dvd the sound is ah ah heh he arar in bits and bats so you cant tell what theyre saying properly also the film freezes at the same time.... what could this be or are the speakers broken, ive done a speaker test through the computer an it saying everything is fine help please...chris.