Macbook pro boot with kernel panic - can't perform kext scan I was trying to swap command and option key for my external keyboard following the instruction in 
http://hints.macworld.com/article.php?story=20110529094802391.

When I'm done with change and I restarted, my mac booted with Kernel panic message. I'm sure I've messed the info.plist file. Now I cannot boot in safe mode as well.

I know if I get a way to change the file it should be fine.

The message shown in screen is 

panic(cpu 0 caller 0xffffff80002c4794): Kernel trap at 0xffffff80005eae1e, type 14=page fault, registers: ...
Debugger called: &lt;panic&gt;
Backtrace (CPU 0), Frame : Return Addressd
...
...
can't perform kext scan: no kext summary
BSD process name corresponding to current thread: Unknown

Mac OS version:
Not yet set

Kernel version:
Darwin Kernel Version 11.4.2: Thu Aug 23 16:25:48PM
Kernel UUID: ...
System uptime in nanoseconds: 11...


The error specifies the problem in kext as well.

Thanks.
The safest thing to do is boot into OS X Recovery and re-install the OS.

You could alternatively boot into Recovery and open terminal and hope to fix the format of the kext file on disk, but I'd say it would be safer to start that Mac in target mode and copy in an unmodified copy of IOHIDFamily.kext into /System/Library/Extensions

Unless you have a good backup of the Mac, it's safer to just reinstall the core OS which will leave your user files and accounts alone, but remedy this system file that is needed for the system to run.