After logging in, and typing startx, X appeared to start (as in I could see the
X cursor and familiar grey window) but then it exited with /tmp/.ICE-unix must
be root. This could be a GNOME issue as well...
My /tmp is cleared at boot time, so next time I did a mkdir /tmp/.ICE-unix as
root, switched back to user and typed startx again.
I got an error stating that /tmp/.ICE-unix has to be mode 1777.
After setting that, X started up fine.
This is in the release notes.
"The socket directories created in /tmp are now required to be owned by root and
have their sticky-bit set. If the premissions are not set correctly, the
component using this directory will print an error message and fail to start."