[ubuntu] How do I use CTRL keys in Virtualbox (I've tried the 'solution' and it doesn't work).

This has been asked before but the solutions do not work for me.

I am using Ubuntu 12.10 in VirtualBox. In the terminal, none of the CRTL keys work e.g. CTRL C provides a 'c'; CTRL V provides a 'v'. This happens whether I use the left or right CTRL key.

People suggest turning off the "show position of pointer when mouse key is pressed". I've done that and it doesn't change anything.

Any ideas? Many thanks!