I tried to drag my usual boot drive (I had booted off another internal drive with system 10.5) to DropDMG in order to make a bootable dmg, and it gave me the following error:

Error File '/Users/jackbodgerLP/Desktop/G5TowerHD_temp.dmg' doesn't exist. for “G5TowerHD”

How do I get a bootable image of my usual boot drive?