No, I did not get a reply, but did find a workaround using the steps as described in the Note shown below which makes use of ssh tunneling. I guess the java console works the same way, but just fails to start for unknown reasons (java 64 bit issue and/or Windows 7?).
How To Access Guest Console In OVM 3 Using VNC Without Using OVM Manager [ID 1548825.1]
Per Oracle's website - RAN into this a few hours ago...Do it as ROOT on the VM Manager Host
It is preferred that you install either TightVNC on the Oracle VM Manager host computer. You can get the latest TightVNC package from:
Install TightVNC with the command:
# rpm -ivh tightvnc-java-
The RAS proxy applet used to view the screen or console of a virtual machine looks for RealVNC by default. If you have multiple VNC viewers on your client computer, you can configure which one is used from the virtual machine console in Oracle VM Manager
so, I guess you might multiple VNC viewer and check if RealVNC is available on Windows client (host C) or check which is used on VM Manager itself (Host B) .and configure it accordingly ,To configure which VNC viewer to use, they have given the few details here