out of sync

Hi, I am having trouble with the audio sync on Videos made with Nero 7 Ultra.

Here is the equipment list. ( and how I have it connected )

Video recorder ; Aiwa mx100 multi system playing a pal video and converting it to ntsc.
Video Camera ; Sony dcr-drv320 ntsc used to pass though the signal as a dv connected to the recorder via rca connections and connected to the computer through firewire
Computer ; Dell xps600

The video recorded by the computer using Nero capture and saved as avi is perfect. NO sync problem after a 3 hour tape was captured. This is the same if I use Windows Movie Maker.

I the use Nero vision to edit the video and export it as a dv, the result is out of sync which gets worse as time goes by. If I save as a dv in Movie Maker the sync Is OK.

I have tried various formats and the results have been the same. I had Roxio and had the same problem, that's why I purchased Nero.

Please advise

Regards Dave Crawford