Cannot Boot from External Drive ONLY on my Macbook Pro?!

Discussion in 'MacBook Pro' started by appleee, Oct 23, 2011.

  1. appleee macrumors newbie

    Sep 22, 2011
    Alright heres the situation, I recently got a Macbook Pro (Late 2007) from a friend for free, and I wanted install Lion on it to use it. The Super drive doesn't work , and the internal HDD sata cable is broken, so I have to boot off an external USB HDD. I made a bootable USB with Lion on it, and while it worked with my Macbook Air, when i try to boot from the usb on my Pro, a gray circle with a line through it appears, and it cannot boot. I decided to just boot using my air and install Lion on my external using my Air, but after I installed, my Pro STILL couldnt boot from the HDD , it had the same error, the circle with the line through it. The HDD works fine, and I can boot normally from the external with my air , but not the pro. Any ideas, I am stuck and really want this to work :(
  2. Mojo1 macrumors 65816

    Jul 26, 2011
    Some external enclosures do not allow booting a Mac. It has to do with the chipset used in the enclosure... I ran into this problem with an Iogear enclosure a few years ago. I had to return it for a version that did allow external booting. Sometimes the enclosure specifications will indicate it will allow booting but most of the time there is no information about Mac booting compatibility.

    Since then I have stuck with enclosures from Other World Computing. Being a Mac specialist outfit, its enclosures have always worked as expected with my Macs.
  3. appleee thread starter macrumors newbie

    Sep 22, 2011
    I can boot sucessfully from my Air, but not my Pro, so I dont think the HDD is the problem
  4. Mojo1 macrumors 65816

    Jul 26, 2011
    Sorry; I missed the MBA reference in your post...

    Considering the other problems the MacBook Pro has, it may have something wrong else wrong with it. I'm assuming that you have at least 2GB RAM in it, because that is the minimum required for Lion. If you attempt to install Lion on a compatible Mac with less than 2GB RAM an error window appears on the desktop. I don't know what would happen if you attempt to boot an external drive with less than 2GB...
  5. appleee thread starter macrumors newbie

    Sep 22, 2011
    Just checked, I do have 2gb of ram. Do you think that Lion just is not compatible with the Pro? It is from 2007
  6. Mojo1, Oct 23, 2011
    Last edited: Oct 23, 2011

    Mojo1 macrumors 65816

    Jul 26, 2011
    If it is a 2007 MBP it should be compatible, because it would have a Core2Duo processor. CPUs before the C2D are not compatible:

    Mac OS X Lion System Requirements
    In order to install Mac OS X 10.7 you will need:

    Intel Core 2 Duo, Core i3, Core i5, Core i7, or Xeon processor
    2GB of RAM
    Mac OS X 10.6.6 or later with the Mac App Store installed
    At least 4GB of additional disk space to accommodate the download, but more is obviously recommended

    There are some hardware problems that can prevent a Mac from booting from an external drive. The MBP optical drive is shot and the internal drive cable is kaput; did it get run over by a truck? ;) At this point I'm suspecting another hardware problem...

    Hopefully someone will come along with some insight into the problem. In the meantime you should consider posting your question on the Apple forum; you may have better luck getting an answer.

    Good luck!
  7. appleee thread starter macrumors newbie

    Sep 22, 2011
    alright I posted it on Apples support page, but I have a feeling it will take awhile, anyone else have any ideas why this would happen?
  8. peetyrd macrumors newbie

    Feb 11, 2011
    Your computer may have its firmware password protected. It would lock any startup keys (holding down C to start up from external drive, resetting pram etc....) when the original hard drive is not connected to the computer.

    Here is a link that shows how to disable:

    However, you're going to have to boot internally from the hard drive that you got the computer with.

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