To Boot your mac from the disk drive, hold the "C" key at start up... right...?? Well I put my Leopard disk in (labled "For Mac Computers Mac OS X Install Disk 1", beneath it says it's version 10.4.8) and held the "C" key in countless different ways each time at start up to get the semi-leopard restore screen and instead my computer just reboots after about 5-10 seconds of holding the key. This is just repeated each time.