If you would read the README file that came with the 3.3.1 KDE, you would know that it crashes if Root is the last one to log out of it.
Running X as root?! Bad Vemc! Bad doggy!
My system starts into KDM, my first and last user to login/out is non-root : no problems for me.
*"first and last" - what the hell does it mean?
I use Multiple X screens for multiple users. See here
for more detail