Ok my dad has started getting a weird problem with videos on his computer ever since he downloaded an mkv of a well known recent release. He cannot hear dialogue, only background sounds and music. It makes no difference whether he's in windows media player or VLC and we have tried messing about with the audio properties and making sure it wasn't set to 5.1 etc (he only has stereo desktop speakers) It doesn't do it with streaming stuff online. He has a soundblaster and onboard realtek 97 sound and they both do the same thing. He's reinstalled VLC and updated drivers and we just cannot figure it out.... it's win xp by the way..... Any ideas what this could be?