Recently I had an Xvfb session in place, using x11vnc as a connection method. Upon login, I saw the following errors:
Error activating XKB configuration. Probably internal X server problem. X server version data: The X.Org Foundation 60802000 If you report this situation as a bug, please include: - The result of xprop -root | grep XKB - The result of gconftool-2 -R /desktop/gnome/peripherals/keyboard/xkb
Ultimately the problem was fixed by adding the -kb option to the Xvnc line in the /etc/X11/gdm/gdm.conf file:
... [server-Standard1] name=Standard server command=/usr/X11R6/bin/Xvfb -kb -ac -screen 0 1280x1024x24 -pixdepths 24 flexible=true