Most likely, you need to download an audio codec or filter for the movie file you are trying to convert. Depending on the type of movie file, you would need something like an AC3, VFW, ACM, DirectShow, RM, QT, or some such other file which causes your converter to properly decode/encode the audio file during the conversion. After you install the filter, you will then need to play with the settings to get it to work with the 4.00 converter. When it's all said and done, you will end up with a solution that works only some of the time at best. It is a hit-n-miss success rate that you just have to try for each video file you desire to convert. I think as time goes on, there will be better solutions, but for now this is the best I have been able to achieve and it seems true for others as well.