I have a HP laptop dv4 series, and with Vista, my laptop speakers worked fine. I usually have the laptop hooked up to my tv, and it plays through the tv speakers. I can not get my laptop speakers to work now. I don't know why they don't work, they do not even show up on the list of playback devices, and if I do not have speakers, headphones or the HDMI cable plugged in, it says I have no sound. Help?