I was rebooting my early 2011 MacBook to run a hardware test on system boot using the shift key. It all went well and the hardware test was accomplished. I rebooted as usual and I get a circle with a line through it instead of the Apple symbol.

Regardless of whether I am booting in safe mode it doesn't boot.

I did the hard disk check and privilege repair which had some complains of that got fixed.
I can't get the system to run. I don't know what a reinstall from recovery will do to my stuff or the machine. What's lost?

Here's a picture of the kernel panic:

  • Reinstalling the OS will only affect system files, not your files.
    – Ruskes
    Aug 11, 2014 at 9:54
  • What about Programms installed?
    – useDuser
    Aug 11, 2014 at 10:00

2 Answers 2


You know the answer already.

For some reason your booth sector got scrambled.

You could try to the reset EFI to see if it helps.

An EFI (extensible firmware interface) is a set of instructions stored in computer memory that act as an interface between computer components and the operating system during startup. If you are having startup problems or your computer components do not work properly, you may be able to solve the problem by resetting the EFI to its default settings.

Read more : http://www.ehow.com/how_8007618_reset-efi-chip.html

Reinstalling the OS with CMD-R will only fix the system files and not your files. It depends if you have the Restore on your hard drive or you need to use the Internet recovery.

  • We'll yes - and thank you to you as we'll || I of course had that done very before getting On this this board posting about me desolve about this. I assume to be able to recover from disk - regardless of Mac requiring network lookup for being a pain in the tip at last (-: ? A joke ... But what differences would it make if network driven vs client sided this is done ? ( I don't have a time machine snapshot ... If that's what you ment)
    – useDuser
    Aug 11, 2014 at 10:37
  • [update]PLEASE SEE IMAGE IN INITIAL QUESTION: on very top. how knows whAt the machine is telling me ??
    – useDuser
    Aug 11, 2014 at 10:42
  • I could not know what else you tried! So if the EFI reset did not help then reinstall the OS. Your screen shot confirms that the boot sector is broken.
    – Ruskes
    Aug 11, 2014 at 11:07

Reinstalling OS X using the Recovery HD will only replace system files. This includes everything in /System, but will not modify your personal files in any of the /Users folders. /Applications that are part of OS X will be replaced, so if you have made any modifications to the system applications they will be overwritten, but your own apps that you've placed in /Applications will remain.

  • we'll in first place I got to hear what I wished to hear - and quite fast - thank you:: never the less I would like to understand the basic issue a bit more / why is it occurring from what,what can be done .... Years ago with windows 95 at some point you did know if run.dll got lost how to manage it with a shorthand... someone there having the close up on this + feels like giving a short for nonGeeks ??? (-:
    – useDuser
    Aug 11, 2014 at 10:20

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