When Xserver starts, at last line in the /var/log/Xorg.0.log file, I found the following some sort of error message.
Could not init font path element /usr/share/fonts/X11/TTF/, removing from list!Could not init font path element /usr/share/fonts/X11/OTF, removing from list!Could not init font path element /usr/share/fonts/X11/CID/, removing from list!I changed /etc/X11/Xsession to /etc/X11/Xsession.xfree86 due to
the result of googling. Then /etc/init.d/gdm restart. The error messages was disappeared.
2007.03.19
This might be wrong solution about this problem. Later when I checked the log file, I saw the same error message.