mac osx 10.5.8, have mac g5 powermac, g5, 2.5ghz quad. wont let me boot up. i did both safe modes, holding down shift key and the option while rebooting. On screen the apple emblem comes up for a second, then the screen went back thru the end of the booting. I’m trying to bring up the startup disk, but not happening. It’s been a while since I’ve been on my Mac. I can’t remember when I first downloaded the Leopard 10 version, did it come in a box or order it online? Sorry about that. Any help would be appreciated! David