I have installed rEFIt on my new 17" MBP so I can boot of a couple of external USB hard disks. I have one with Windows 7 and one with Ubuntu. Both boot fine on my 2009 13" MBP. The problem is that as soon as you try and boot from either of them the USB ports seem to shut down causing the external disk to spin down. The Mac (or EFI) then decides its ready to boot the selected OS. Unfortunately the disk doesn't spin up in time or doesn't spin up at all and then it craps out saying it cant find the selected disk. I think this is because the USB ports haven't 'come up' again. The mad thing is that this happens even with Mac OS X on an external USB hard disk! Could another kind forum member help me out and try this on a 2011 model? Do you get the same results? Any ideas what's wrong? I did try and side step the problem by using Ultimate Boot CD with Grub2 but it wont even detect the disks (only the internal). I tried it with the 13" and it does detect them so it definitely looks like somethings screwed up with USB on this thing.