The Nav is VERY sensitive to the way the DVD is burnt. Most people find that using a good quality DVD, like Verbatim, burnt at the slowest speed you can will work. However, if I do that with my DVD burner it does not work, I have to burn at 16x otherwise it won't work. Bottom line is, it's trial and error - to make sure you can burn the disk, try making a direct copy of a known working disk first.