I just did apt-get dist-upgrade, seems the upgrade process went well, and it brought up the GRUB memu at the end, I choosed the 3.18.0-kali3-amd64 option to boot, it brought up the login GUI shortly, after I entered the root as user name and my password, it does not allow me to log in, saying "sorry, it does not work, please try again". well, I tried to use ssh to log into the machine within my home network, I'm able to log into the system as root by entering the password without problem.
I think the problem may be related to the upgrade/installation process, somewhere I did not select the correct option. Does any one know how to fix the login problem?
Note, after the dist-upgrade, it shows it upgraded to debian 8.
Thanks a lot for help.
Dave