Try to keep it down to 2 on the first outing.
My dvd burner on my computer is a Pioneer DVR-106A. The fastest for dvd-r's is 4x. I'm running winxp and using nero to burn it. I have used generic blank dvd-r's in the past which works very well, but i ran out so i got new ones which are Memorex DVD-R 16x. Firmware for the burner HAS been updated.
When i burn an dvd iso image onto the blank dvd-r, Nero does it without errors. But when i look at the disc that i just burned (through windows/mycomputer/drive), it says it is a CD instead of a DVD and it has 0 free space/0 used space. my GUESS is my pioneer burner is too old to work with a 16x (even though i thought a firmware upgrade would have fixed it), but i dont want to throw $100 at a new burner if i dont have to. can anyone tell me what is wrong?