problem with audio during playback of video burned to disc

I imported video from my digital camera. The video and audio are fine during
playback using quoictime (I can no longer view them using windows media
player nor anything for that matter), but after burning thwm using NTI CD
DVD Maker, when played back from the DVD the video plays fine, but I get only
about 3 seconds of audio at the beggining then nothing. I used to use WMP to
burn my videos and it worked ok exept one batch where the audio was very
choppy. Recently, I must have done something because all my JPEG files are
now MOV files and that seems to be when the problem with the audio occured. I
have downloade different file converters to see if I cold convert them so I
could use them with WMP again but couldn't convert them. I am getting
desperate for disc space btu can't delete these videos until I have them
burned off in tact. I need help. I am using Vista Home Basic 32bit and am new
to computers.
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MAJ-123