[...] The shortcut is still set correctly to /,
but nothing happens when I press the / key.
Is this a known problem, or if not then how can I debug it further, please ?
oh wait. I had a problem similar to that about 6 month ago. it did not affect '/' but some other keys - they were swallowed/remapped by some unknown reason (xine was affected and some other apps, too). It turned out to be some strange config issue with a certain version of X and trinity (the problem did not show up with fvwm). I finially got rid of it with a complete new installation of squeeze, a new X, and I jettisoned my old configs.