Liteon LVW 5005 DVD Recorder Help

I bought the PAL version (Australia) but while I was in the USA I bought a DV camera hence all recordings are in NTSC.
Last night I did my first dv transfer to dvd. The recorder to set to NTSC. The weird thing is while I was recording, I was viewing the dv tape on my TV. There were laser dropouts (sound dropouts) during the entire tape. My fears was the end results recorded on dvd (dvd-r tdk) would also have sound dropouts. to my surprise the dvd was fine, well except for the last ten minutes I had a bit of freezing.
If I stop recording, but continue to let my dv camera play and I continue to watch that dvd tape on my tv, there were no sound dropouts.
Why does this happen? A buffer problem? Laser head problem? Or media problem?
Many Thanks