Help! - Lion modified disk I was installing from.

Rather strange event here, but I thought if anybody could help, they'd hang out here.

First, some background: I have an old (4+ year) MacBook Pro that got me through college, and I'm a few months to a year away from being able to replace it, monetarily, at this point. About a year ago, it began to exhibit some odd problems with freezing (immediate, complete freezes, cursor stops moving, most of the time there isn't even an error report). I found that they happened far less regularly when the computer was plugged in (perhaps once a month compared to every ten minutes on battery). I also discovered when trying to reinstall Snow Leopard that something in the install process will lock it up, every time. My fix then was to boot my mac in target disk mode, and install Snow Leopard using my girlfriend's computer to run the installer.

Fast forward to Lion, and I'd somewhat forgotten about the problem, as my computer is a de facto desktop now. I wanted to do a clean install, so I booted Snow Leopard from my backup image on an external HD, formatted the internal drive, and pointed the installer to that drive to install. Inevitably, it froze, reminding me of the problem. Unfortunately, the installer appears to have modified the boot parameters for the external drive in some way, because it boots the recovery environment now, and not Snow Leopard. All my original data and the 10.6 system are still present on the drive.

I had Lion installed onto my internal drive at the Genius Bar via the target disk mode approach described above, which worked, but I find it freezes in less than 2 minutes from boot, every time, plugged in or not. However, if I boot into safe mode (as I did when writing this), it will work indefinitely without freezes.

So, I'm looking for help with one of two things:

1. Any suggestions on what could be the root cause of the freezes, and how to fix it on the Lion installation?

2. Any idea what Lion did to my (formerly) bootable external drive, and how to convince it to boot the 10.6 system on the drive? If I can manage that, I can Carbon Copy Clone the external back to the internal and at least run 10.6 on it until such time as I can afford a new Mac.

Thank you for reading this long post, and for any suggestions you have. I've been through quite a few attempts, but I'm lost at this point. Let me know if there is any additional information I can provide that may help, as well.


--Alex

 

Yup. Selecting the external boots the recovery environment. On the external drive, there is a hidden folder on the root of the drive called .IABootFiles with a com.apple.Boot.plist inside. Its contents follow this post. There is also a kernelcache in the folder. It seems obvious this has something to do with it, but renaming the .plist, clearing the parameters, replacing it with my original from /System/Library/SystemConfiguration, replacing the kernelcache with the one in my /System/Library/Caches/com.apple.kext.caches/Startup/, renaming the .IABootFiles to take it out of the equation all result in either an immediate black screen and reboot, or a flashed "no" (Circle with slash), then booting from the internal (Lion) installation.

 

Just trying to get this in front of some different eyes since the forum is so active right now.

 

After innumerable tests and reboots, finally got it fixed by basically blowing up the boot.efi from the .IABootFiles folder of Lion, then blessing the old 10.6 /System/Library/CoreServices folder and using the bless command to generate a fresh boot.efi.

Phew. Time to clone back to the internal, and sadly say goodbye to Lion for the near-term.