control swapping not working

[m h]

(I'm not sure if this is an X issue so feel free to point me somewhere
more appropriate :))

I've got ubuntu 10.4 running under virtualbox 4.02 on a macbook pro.

The mac has the caps lock and control switched.  So when using the
laptop keyboard the caps lock key effectively serves a control key.

When I plug in my usb external keyboard the caps and control key on it
are not switched.  So I ran the following under ubuntu::

setxkbmap -option ctrl:swapcaps

Now the control key on my external (and the laptop keyboard) serve as
a caps lock key.   But.... the caps lock key doesn't serve a a ctrl
modifier.

When I run xev, it registers the control key, but when I combine it
with another key, say ctrl-a it only recognizes the a.  (state in xev
is 0x0 instead of 0x4).  The right control key in combination with an
a shows the state as 0x4 and appears to be the only functioning
control key now.

I saw that someone was having similar problems 2 years ago with an
adesso keyboard.  My keyboard is a unicomp endura pro and the reason
I'm confused is that I've been using it with a thinkpad t61p on gentoo
and didn't have any issues with the swapping there.

Any ideas?  hints?

thanks much,

matt