How to avoid buffer underrun?

I have just bought a new G5 Mac, Dual2,3GHz (before they announced the Dual-Core..), but I am getting buffer underrun errors when trying to burn a HD DVD project to DVD??? It probably happens due to the DVD media I am using, that is of a cheap quality, and I have had to burn normal datadiscs at a lower speed (4x) to get a fault-free DVD. Now when I do this via the OS, I get an option to use a lower burning speed, but when I do the burning from within DVDSP I do not get an option like that.

How can I control the burning speed within DVDSP?

If this is not possible, then is it possible to "Build" to a folder, then use "the common OS X burning software" to burn this folder to DVD and still have a commonly readable DVD??

And last, How can I avoid buffer underrun in general?

THX All..

Can somebody please help here?

I can't burn any DVD's via DVDSP 4 and the superdrive in a new G5 2,3GHz PowerPC. The brand new Mac can also not burn ordinary datadiscs at 8x speed (?!), but when I lower the speed (manually) to 4x burning speed then it works.
But how do I control the burning speed from within DVDSP? Does this option exist within DVDSP 4 at all?

If I could control it, and set it to 4x burning speed, I could at least burn properly formatted DVD's just taking a bit longer time, rather than now when I can't burn at all!!

As mentioned I have tried burning a DVD straight from the Build folder (following the instructions in the manual for DVDSP 4 on page 567) but somehow it doesn't format the dvd disc correctly as it will not play automaticly on my Mac, some PC's, and on some Stand-ALONE DVD PLAYERS. If the Mac's internal burning program can't format a DVD correctly, would Toast be able to? Would DVDSP 4??

Thanks