First of all, RH9 is no longer supported by RedHat and this means that there will be no new security updates avaialble. If you don't have a good reason to stick to RH9, it is suggested to switch a more modern distro.
To the problem:
I haven't use RH for ages (I've still RH8 installed somewhere), so I'm not sure what RH9 uses (I think it's XFree86). Therefore this might nmot be 100% accurate
Can you please provide details about your monitor as well.
There should be more info on the actual error. Check /var/log for files related to X. Errors are preceeded by (EE).
Please post sections device, monitor and screen of your X configuration (some where in /etc/X11 or /etc/XF.... )