Can't Log In -- Computer Keeps Restarting

Today, when I logged in to my MacBook Pro (2012, Retina display), the screen went black and I got a message that said (in multiple languages):

Your computer restarted because of a problem. Press a key or wait a few seconds to continue starting up.

See the below image for what the message looks like:

When I wait for the computer to show the log in screen again and log in, I get the same message. Basically, I can't log in to my account.

Does anyone know why this is happening and how I can fix it?