Audio Distortion

I am new to trying to create DVDs from video I have taken myself. (Canon MV630i digital camcorder).

I can produce very good quality video in mpeg-2 and in wmv but when I burn the Video (either format) to DVD I get horrendous audio distortion.

I have tried burning using DVD creator, Pinnacle Studio 7, Power Director, Ulead studio 7.

I am using hero dvd player on my PC to play the DVDs. Video reproduction is fine. Audio is crap. I thought it might be a problem with background music which I overlay on a lot of video clips (muting the video track) but it happens even without an overlay sound track.

Are there any special audio codecs or decoders which I may not have installed?

Any suggestions would be gratefully received before I go completely mental.

Brendan (bren2310)