I have installed RHEL5 server from the sets of 5 CD's I had from RED HAT. During installation only 3 CD's were used. I am unable to have a GUI mode on the screen. The moment I use Startx from the default mode 3, the PC shows a blank screen, my keyboard doesn't respond and i am unable to use alt+ ctrl+ f1 or others to switch back to text mode. I have to reboot the system by witching it off/on. what all rpm packages should i look for. Can it be a monitor problem.I have also set my DISPLAY variable to localhost but it diddn't work. How should i go about troubleshooting this issue.

Did you run 'system-config-display' or make changes manually to configure your display after installation? What does /var/log/X*.log say (egrep for EE and WW lines)?

at the time of reading the reply from you, i havn't yet tested the egrep option but yes i did go for system-config-dsplay and dit also led to the blank screen and my keyboard input wasn't accepted and I have to reboot by switching off/on the system.
I will go thru the /var/log and report back to you.
thanks for replying

Is the xfs service on??
startx would report error if xfs is not running.

Are you sure you chose the GUI option at install time?
If this is a brand new system, maybe re-install and go slow, check all qns carefully.