Hi all, This is my first time posting here, hope someone can help..thanks.. I do not have any audio output on my Macbook Pro when running on mac os. However, there is still the start up chime sound. It shows a stop sign when I tried to increase or decrease the volume. Sound panel shows 'no audio output'. No red led light from the headphone jack as well. However, when running window 7 on bootcamp, I do have audio from my internal speaker and there is a red led right from the headphone jack. Headphone works.