Cannot boot Mac after installing a .plist file

Question

Hi,
I have a MacBook Pro using latest OS and had been having trouble with my wallpaper changing back to default settings. After reading this support thread: https://discussions.apple.com/thread/4144290?start=0&tstart=0, I followed the instructions to install the following file in this directory:
Library/Preferences/SystemConfiguration/
The file called autodiskmount.plist had the following content (all following the directions of the thread above):
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="0.9">
<dict>
<key>AutomountDisksWithoutUserLogin</key><true/>
</dict>
</plist>
After trying to restart the laptop, it has now been stuck at the grey screen with the apple logo and the rotating circle. I have tried using disk utility and repairing the start up disk. Doing a safe reboot does not work.
Any  advice on how to repair my Mac and successfully restart it are more than welcome!
Thanks!

Answer 1

Restart the computer with the Command and S keys held down and run the following:
mount -uw /
mv /Library/Preferences/SystemConfiguration/autodiskmount.plist /Users/Shared/autodiskmount.plist
exit
If you're able to log in successfully, open the /Users/Shared/ folder and then delete the file. If you overwrote an existing file, you may need to replace it, which may require reinstalling Mac OS X.
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