Reset password screen always comes up

Question

After updating to Yosemite, most of the time when I turn on my MacBook Pro, the "reset password" screen appears.  The only options I have are not relevant. I have not forgotten my password and don't need to reset it.  However, because I need to access the info on my Mac, I play along and reset.  The next time I turn on my Mac, I usually get a black screen or the "reset password screen" screen again.  This never happened before the update.  I cannot find an answer anywhere.  Please help!

Answer 1

Try booting into the Safe Mode using your normal account.  Disconnect all peripherals except those needed for the test. Shut down the computer and then power it back up after waiting 10 seconds. Immediately after hearing the startup chime, hold down the shift key and continue to hold it until the gray Apple icon and a progress bar appear and again when you log in. The boot up is significantly slower than normal. This will reset some caches, forces a directory check, and disables all startup and login items, among other things. When you reboot normally, the initial reboot may be slower than normal. If the system operates normally, there may be 3rd party applications which are causing a problem. Try deleting/disabling the third party applications after a restart by using the application un-installer. For each disable/delete, you will need to restart if you don’t do them all at once.
Safe Mode - About
Safe Mode - Yosemite
If that doesn't fix it, do a backup. Boot to the Recovery Volume (command - R on a restart or hold down the option/alt key during a restart and select Recovery Volume). Run Disk Utility Verify/Repair and Repair Permissions until you get no errors. Then re-install the OS.
OS X Recovery
OS X Recovery (2)