I am playing .avi and .mpeg files on quicktime with my macbook. I downloaded about 12 episodes of one show. All of the episodes play with audio except for one of them. I thought that this files was corrupt, however when I transferred it to a windows based pc it played fine. I downloaded the show again and then played it on a windows based machine. When I transferred it to my mac, same problem picture with no sound. Any ideas? I have tried to download an audio codec for mac, however it did not see to help.