Does anyone know the difference between DVD - & + R DL disks? I have just created 2 perfect coasters (write errors ) using Toast to copy my Snow Leopard Install DVD (Dual Layer) using DVD+R disks. I did the copy at 4X (disks rated up to 8X) on my MacBook Pro which says it supports DVD+R DL, and the DVD-R DL disks are really hard to find. Haven't tried using Disk Utility yet, may or may not work with the toast image file I have. Is the original SL disk a DVD-R DL and is that the problem? Any advice appreciated.