Nero and BenQ

Hi,
I am having terrible trouble trying to burn dvds with nero. My burner was originally a Philips 8630 but I have recently flashed it over to a BENQDW1620, having seen the suggestion here, to see if it helps but to no avail. I am trying to burn DVD-R’s and each time it burns to about 25% and then faills, any ideas??
Thanks
Colum