halo 3 on my xbox 360 is having sound problems when im playin on campaign. when the sound does work it skips and there is none for a moment, then its back all at once. and now there are no voices but i can hear all the backround stuff...it is not the 360 because when i press start i can hear all those sounds when you move around the menus..anyone had similar problems or have ne idea how to help me w. this?