The hard drive died on my 24" aluminum Imac. When I try to start up off my Leopard disk the Mac just keeps rebooting over and over. I was told this might be caused if the electronics on the drive had been fried. I bought a new drive and installed Leopard from another Imac externally. Installed the drive and the same thing. A couple of years before the crash I had installed Snow Leopard on this machine (the disk is now cracked). Now I've been told that Snow leopard wrote info to the ROM and I can't go back to Leopard. Anyone heard of this or have any ideas?