After updating Oracle Linux 6.3 to 6.4 or installing 6.4 from scratch will give a corrupt (blank) VNC remote console when launching the console from Oracle VM Manager:
As discussed in https://oss.oracle.com/ol6/docs/RELEASE-NOTES-U4-en.html#idp513536 and Oracle Support note ‘Corrupted VNC console in PVM guests running Oracle Linux 6.4 on Oracle VM’ (Doc ID 1537278.1), this issue is addressed in ‘X Window System Does Not Run in a PVHVM guest’.
Uninstalling the xorg-x11-drv-cirrus guest driver solves the issue
If you uninstall the xorg-x11-cirrus driver from the guest OS, it will solve this issue.
# rpm -ev --nodeps xorg-x11-drv-cirrus
Reboot the server after uninstalling.