first of all, Arunshivanandan, thanks for helping.
anyway, my problem is
i was trying to install redhat 9.0 on my pc, but when it finished the installation and rebooted to initialize the system environment, my monitor kept flashing several times and gave me an error message: "failed to start the display server several times in a short time period; disabling display : 0 ", it seems i couldn't get into x window by this way.
So, i tried single user mode and typed "startx" to run GNOME to see what happened. hopefully, i could use GNOME, but it raised another problem. the new problem is when i tried to run any programs, an error message popped up: < Application "nautilus" (process XXXX <-- 'XXXX are some numbers' ) has crashed due to a fatal error (segmentation fault) >
And i also checked /var/log/XFree.0.log, i found there was no error there.....
anyone can tell what is going on?