chef… I didn’t create the ISO myself, it’s a download.
But… I’ve done some research and tried a different brand of media like Liggy suggested.
With Maxell DVD-R media (RITEKF1) I initially burned the same ISO at 8x speed and got a good result. So I also tried 8x speed with the TDK DVD+R media to make sure it wasn’t just a speed problem, but with the TDK’s it still didn’t work.
I then burned a Maxell DVD-R at maximum speed which also gave a good result.
So, it looks like my burner either has a problem with TDK media, or with DVD+R in general. Does that make sense?