Problems with sound

first off im not really sure if this sound issue qualifies as hardware but i really dont know where else to try


ok i have currently two Pc's they both work normal and fine

i am having an issue with sound

i downloaded a video my first PC has no problems with video or audio

so i put the video on my portable HD and take it to the other PC play the same video

the Video part is fine but there is no Audio

now both PC have working audio and this seems to be the only video file with this issue all other video work fine in both video/audio

anyone know what the problem might be ? any help is appreciated