Right since the beginning then my Natty partition has had this problem, where if I press any key on my keyboard the interface freezes.
I have been able to painfully work around the problem by using chroot to update the packages, but also going Ctrl+Alt+1, logging into this, and going back to Ctrl+Alt+7. (This is a slow process but afterwards it stops freezing).
This problem certainly predates the new Compiz and new Unity.
(The problem has persisted since I got a new keyboard and mouse.)