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I have a strange issue on an early 2008 Mac Pro running OS 10.6:

  • if I restart the computer it restarts normally
  • if I shutdown and boot, it stops at the grey screen just before the boot process
  • if I shutdown and boot but hold down the option key, I can select the boot disk and all is good.

I've just cloned the disk, and the same thing happens.

  • The disk is a SAMSUNG HD154UI
  • The disk is partitioned (the second partition holds a clone of the Snow Leopard Install disk)

One weird thing on the original disk was one of the partitions said 'EFI Boot' in a non-aliased font rather than the name of the disk when the disks are listed upon holding down option.

Solution: it seems that there was a problem with the disk. Part of the difficulty in finding the solution was that you need to remove the disk from the computer completely. For example, a good disk in Bay 3, wouldn't boot up if the bad disk was in Bay 2. So for ages I thought the problem was hardware related in Bay 3. So if you think you have a dodgy disk remove it totally if you are testing the hardware with a 'clean' disk. Cleaning the PRAM helped to get the new disk to work too.

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Do you use Disk Warrior? If so, does this apply? – Daniel Beck Mar 11 '11 at 5:56
up vote 3 down vote accepted
  1. Once you've booted into Mac OS X, go to System Preferences > Startup Disk and select your boot volume. This will cause your preferred boot drive to be stored in NVRAM (PRAM).

  2. If that doesn't work, try resetting your PRAM by holding down Cmd-Opt-P-R at boot until you hear the boot chime an extra time. Then do step 1 again.

If that still doesn't work, then it might be something about how your hard drive is formatted. Use Disk Utility to see if it's using a GUID Partition Table (GPT).

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This didn't actually solve the problem but it did contribute. See edit above. – Gazzer Mar 12 '11 at 14:35

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