When I put my video with a sound attached to it into the timeline it only plays the music and background noise, but when I play the video file on my computer the audio is fine. When I check the properties on the video after inserting it into the timeline it says the audio is compressed so guess this could be why, but I don't know how to decompress it or get the full audio to play.
How did you create the file... what camera did you use?
Exactly what is INSIDE the video you are editing? Report back with the codec details of your file, use the program below Free program to get file information for PC/Mac http://mediaarea.net/en/MediaInfo/Download - when you analyze your file in MediaInfo and post a screen shot in the forum, do so in TREE view