Can burn data, but not dvd-video with MF4?!

[jlunny]

First, my burner works - even with Ulead software (Burn.now) with a data disc.

But if I create a movie with MF4, it gets part way through and I get a "cannot burn data to disc" error. I've tried direct from MF4 to disc, also from MF4 to .iso and then to disc using two different burning software!

I've tried a couple of different simple movies, but I'm inclined to believe the image MF4 is creating is bad (or at least incompatible.)

Any idea?