I'm having some trouble upgrading the newly formatted Mac from its original OS X Leopard. I do not have the SL DVD anymore since I removed the optical drive but I have the dmg I previously generated from it, which I now mounted in an external hard drive and am trying to boot from it. What happens is that I get an error saying OS X was not able to install on this computer. It worked fine installing from the external hard drive with Leopard. Anyone knows how I could possibly fix this? Thanks a lot!