I have windows vista home premium with service pack 2 and acrobat reader X, i have few tutorial pdfs which have embeded audio files. The audio plays but without sound. Other audio files with realplayer, windows media player and quicktime player works fine. I would like to mention here is the same file in windows xp works fine, audio in the pdf plays with the sound. Is there any security privelages which has to be enabled in windows ??? i am not sure.