Boot your system into runlevel 3. Log in as root and type the command /usr/bin/startx. Exit X Window and examine the logfile /var/log/Xorg.0.log. What specific things does this file tell you about your graphical environment? From this file, can you determine what video card you have and what resolutions it supports?
Exit X Window and use the /sbin/init command to change your system to runlevel 5. Once X Window starts, hit the key combination Ctrl-Alt-backspace. What happens to X Window? Why does this happen?