something is eating C-M-x

[Stephen Leake]

I've just installed a new VMWare virtual machine on my Windows box to
run Debian.

Something is eating C-M-x, so Emacs doesn't see it. Very frustrating
when trying to redefine elisp functions!

I'm using the LXDE window manager, and I've checked
~/.config/openbox/lxde-rc.xml; that does not define C-A-x.

I've searched in various ways for "hotkeys" and similar terms, but have
not found what the problem is.

Any hints?

Is there some X debug program that shows how key events are handled?

-- 
-- Stephe