trouble with GUI

Hi,

I have one RHEL6.5 was working fine and suddenly having issue with booting into runlevel 5, it simply hangs after starting rhsmcertd service. below error is reported in the messages.

May 2 15:14:35 cmod95 init: prefdm main process (3060) terminated with status 1
May 2 15:14:35 cmod95 init: prefdm respawning too fast, stopped

I tried different article provided by redhat without any luck.

However, i was able to using runlevel 3 and run "/etc/X11/prefdm -nodaemon " then "startx" will bring me to the GUI interface.

Can someone please help me with the issue?

Thanks,
Denny