I can't get a reasonable volume from movies or websites. Speakers still work, and I am able to barely hear sound from the headphones. For example, a movie from southparkstudios.com starts off working fine, the sound becomes a little garbled, fine for a second and then fails. Itunes seems to work fine and some youtube videos' background sounds/music play fine with a little garbled type sound, but dialog is unaudible, for some I can hear a little sound, and for some all sounds are fine. Also, testing the sound from the control panel works fine. I'm using a Compaq c700 with Windows Vista Home Premium. Please help!