Hi, I have an original retail Leopard DVD. It works perfect on my PPC G4 Powerbook. BUT the DVD does not boot from My Intel Mini (early 2007 model, 2Gb ram). If I hold down Option at startup, the DVD volume is recognized as bootable, I can select it, but than the Mini hangs with a "no logo" startup screen (where the apple logo usually appears). I guess it means it can not find a system to start from. If I hold down C at startup, it simply boots from the Tiger on the internal HD. If I select the DVD volume with the "Startup disk" preferences, then when I press the Restart button in the same preference panel, it does nothing, no restart.. (?) If I hold down Command+Option+Shift+Del at startup, it boots from the internal HD When I run the Tiger from the internal HD, I can easily mount the Leopard DVD. If I run the Leopard installer from there, it starts, then it asks permission to restart, but than it boots again from the internal HD Tiger and no installation goes on. The same Mini boots perfect from the Tiger installation disks, so the optical drive is ok. Indeed I also made a fresh erase and install of Tiger, but it didn't help booting the Leopard DVD I also tried the clone methods, I made an image file of the Leopard DVD and restored it on external HD (I tried both Firewire and USB2, GUID partitioned, or APT partitioned, with single or multiple partition). Then the restored volume is seen as a bootable volume (so it is a good clone of the DVD) but it behaves the very same as the DVD, i.e. it does not boot. After two days of fightingh with that, I see no way how to install the Leopard on my Mini. Am I missing something ??? Thanks for any hint... [later on....] PS: SOLVED !! I got the right suggestion: PRAM RESET . Now it works fine !!!