Ubuntu 14.04 won't login?
 

Trying to log in through the GUI to the desktop that comes with Ubuntu 14.04, I put in the password, the screen goes black, and a few seconds later, it returns to the login screen.

If I use ctrl/alt/F3 to bring up the command line, I can log in fine, run commands, etc. I've tried reinstalling ubuntu-desktop to no avail. Any ideas on what I could do without having to just completely reinstall Ubuntu?

If X crashes and is automatically restarted then I think that that would generate the behaviour you are seeing.
So perhaps try logging in on a non-GUI terminal as you describe, and then look at the X Window System log files?

[url]http://askubuntu.com/questions/537030/ubuntu-14-04-desktop-not-loading-after-login[/url]

I ended up following the instructions in the 1st answer at this link, and it worked. Maybe some kind of issue with nvidia? I had the CUDA toolkit installed, so that may have done it. Just glad to have a proper desktop back.