I have the exact same problem (which most likely is a user problem)
but I was under the impression DVD has 4.7 Gig free space,
so why does it always write it as a CD disc (with 700Meg of space)?
In the picture of above link you see it at the bottom : 700 meg
but I want to put 4 gig of mp3s on the disc! that's why I bought the thing!
so just choosing create data disc always gives 600megs!
can't I create a data dvd disc with 4gig?