Here is my MDD disk setup: On ATA100 controller I have two disks, WD160GB (Master) and Maxtor 20GB (Slave). Leopard (10.5.8) is installed od 160GB and Tiger (10.4.11) is installer od 20GB. And now the boot thing: I can sellect with alt (option) Tiger as boot, and boot it ok, just on power on. After software reset, and option-boot, only Leopard disk is found. And also, when I am in Leoprd and select Tiger disk as Start Up disk in Preferences, again MDD is booting in Leopard. Power On boot menu: Restart boot menu: Is this normal or what is going on ? Is this maybe related to fact that Leo is installed on disk which is Primary master ? Again I can boot Tiger only on Power On and select Tiger as boot with option key.