The Short Story: I created an external bootable drive using Carbon Copy Cloner, but when I restart (holding Alt/Option), the new external bootable drive doesn't appear as one of the options. The Long Story: 1) The iMac that I'm working on is currently booting from an external hard drive (the internal drive died and, since it's an older computer, I didn't want to spend the money/time replacing the internal HD). 2) The current external HD is older and slower than the one I'm trying to replace it with, which is why I'm trying to replace it. 3) The current external HD is powered through a wall plug, while the newer external HD is powered through the iMac (I'm wondering if this is the issue?) -> the "new" HD is actually an HD I took out of a MBP awhile back when I updated my MBP. Hopefully that's enough info to work with...*any* thoughts much appreciated!