Well guys, here 6 weeks later I just came across your posting. I get the exact same message when trying to format a project. However, it doesn't happen when I use the Apple branded 4x DVD-R disc's.
I just purchased a batch of Ridata G04 4x's and it seems that I can't use em.
I'm trying to make a copy now to the Ridata's using Toast.
As I say, I was able to burn a master using the Apple stock.