My USB bootable external HD isn't listed on my "new" G5 (so I can choose to boot from it) when Starting w/ the Option key down. I always booted from this disk on my G4 and don't understand why it's not listed among the bootable choices (not listed as a Startup Device, either). (I actually have two bootable externals, & neither appears, tho both used to.) I even downgraded to the same OS as my externals (10.4.11), to no avail. Does the G5 (iMac) refuse to recognize USB external bootable drives? Any help MUCH appreciated.