[fedora-virt] Keyboard stops working on XP KVM?

[Tom Horsley <tom horsley att net>]

I've just noticed a weird thing on my Windows XP KVM virtual
machine:

If I logoff the current user to get back to the windows login
screen, the keyboard no longer works, but the mouse works
fine. All I can do is use the mouse to reboot the system,
I can't type any passwords to login.

Anyone have any clues about what causes this?