X window can not startup

When the system shutdown and startup, the login window can not start normally and often display as character mode, I have uncomment the last line in the /etc/dt/config/Xservers file as the following, but the problem still unfix:

 *    Local local@console /usr/bin/X11/X :0

another problem is when the system restart, the above file is modified as the origin:

 #  *    Local local@console /usr/bin/X11/X :0

anyone can help me?