JVC DV Camcorder troubleshooting

I have a JVC GR-D770U DV camcorder. Brand new and we've recorded twice with it. (homevideos) and each time the sound on the video starts out clear and then crackles before completely going out. It continues like this through out the entire video. Does anyone have any suggestions as to how I can fix this?

Thanks in advance for any help.

Holly