So here is a corker of an annoying problem. When trying to use VirtualBox machines or Remote Desktop-ed into a Windows machine of even VNC-ed across to another Linux machine the CTRL keys do not work, but does within the host machine. This causes at lot of pain because RIGHT-CTRL is the default VirtualBox host key and obviously CTRL+C is common to both Windows and Linux alike to cancel a running command line launched process or even as a shortcut to copy. The list is endless
So credit must go to a user who goes by the name of mrf76 on the Ubuntu forums who found that it was the mouse locate pointer setting which is activated by pressing either of the control keys. Turn this off and all is well with the world again.