While updating 13.04 Raring Ringtail on a fresh installation my system froze. On reboot I am unable to log in on the graphical screen. CTRL-ALT-F2 takes me to the command line where the login works correctly. I then completed the "sudo passwd" process with positive results. On returning to the graphical screen I saw no change in accessing the account. I suspect something was corrupted during the crash. I'm too new at UBUNTU to know where to look, much less what to do in order to straighten out whatever was broken.
All advice, step by step instruction, etc. much appreciated. My fall back is to reinstall the OS from scratch as it's a new system. Which is more efficient, fix or reinstall? Thanks.