Here is my story I had a MacBook PRO 2010 with Mac OS X 10.8 Mountain Lion since I bought it I've never reinstalled the OS until now. I did a clean install following this instructions http://www.hongkiat.com/blog/clean-install-mountain-lion/
Since then I've had reinstalled twice. Everything works fine for couple of days until I turn on my mac and this image comes up:
What I'm doing wrong why now keeps showing this window instead of booting to Mac OS X.