I have an issue where once in a while the computer will freeze while playing Dota 2. So a few times i did a hard restart to get it going again. Last time i did that, it caused me to be unable to get past the log in screen. The guest account would work, but my main account wouldnt; id enter password, black flash, and back into log in screen. I was able to resolve my issue by clicking "cntrl + alt + F2" , typing in my username and password, and then running the following commands: "sudo rm /home/username/.Xauthority" and then "sudo reboot" I found the instructions here, and if it doesnt work for anyone else that may come across this then there are other things you can try as listed here: http://old.elementary.io/answers/cant-log-in As for the reason why the freezes are happening... appears to be related to nvidia video cards malfunctioning and not being able to recover. A problem that autofixes itself in windows, but becomes a catastrophic problem in linux. More info can be found here: https://www.reddit.com/r/elementaryos/comments/2r4cr6/freya_randomly_freezes/ Users have said that if this freeze happens to you, try pressing "cntrl+alt+F1" and then once the screen goes black, press "Cntrl+alt+F7". I havent tried this yet but will next time it crashes. I believe this is the open bug with no fix; https://www.bountysource.com/issues...to-crash-in-elementary-os-luna-stable-version Seems like a serious issue as it can render your pc useless if you dont find the fixes i did. Hopefully it gets fixed. if it doesnt, I hope this post has helped anyone who is coming here with the same problem. EDIT: so just had another freeze and the solution that was posted actually works. you will get back a usable desktop after a crash if you do whats listed above. pretty neat.