Hi, I want to reinstall Lion without losing data. Ive searched google and this site :http://apple.stackexchange.com/ques...-reinstall-mac-os-x-lion-without-erasing-data claims: Reboot your Mac. When you hear the boot chime, hold the COMMAND + R keys. You will enter the Lion Recovery environment. From there, simply choose to reinstall Lion. It will simply remove the current system and replace it with a fresh copy. None of your data will be deleted or moved. The only thing that will be replaced will be the core system files. There is no longer any need to make backups, migrate your data, or mess with partitioning. Will this truly work ?