iMac will not boot, just a curser

I had this problem and fought it for a week! It would not boot, just got a curser...

This fixed mine:

Restart your machine while holding the "SHIFT" key until you see a progress bar (Safe Mode). A window will open asking which user do you want to use. Select and enter your password. The screen may act strange, don't worry. Go to PREFERENCE's /USERS & GROUPS/LOGIN OPTIONS. Turn on AUTOMATIC LOGIN and select your account & enter password. Reboot and life will once again be GOOD! It seemed to be a thing with OS 10.11.1

Man I hope this helps some of you.