package xorg-x11-server-Xvnc-source-1.1.1-48.76.el5_5.2.x86_64 is already installed

package xorg-x11-server-Xvfb-1.1.1-48.76.el5_5.2.x86_64 is already installed

package xorg-x11-fonts-base-7.1-2.1.el5.noarch is already installed

I am trying to start the Xvfb in linux. I am getting below error.

-bash-3.2$ /usr/bin/Xvfb :5 -ac -screen 0 1024x768x8

Couldn't open RGB_DB '/usr/share/X11/rgb'
_XSERVTransSocketOpenCOTSServer: Unable to open socket for inet6
_XSERVTransOpen: transport open failed for inet6/ne1-cimpa-004.adx.pool.corp.ne1.yahoo.com:5
_XSERVTransMakeAllCOTSServerListeners: failed to open listener for inet6
error opening security policy file /usr/lib64/xserver/SecurityPolicy


Any tips for this problem