System:

Debian release 5.0.1 (lenny)
Kernel Linux 2.6.26-1-686
GNOME 2.22.3

History:

Used netinst feature with expert graphical procedure to install OS without any proprietary firmware, drivers, software on three systems.

Using stable repositories with lenny main, updates, and volatile enabled.

I have not seen the problem in the GNOME desktops on MEPIS, Mint, or Ubuntu on any of these computers.

Problem:

The keyboard shortcuts for "Lock screen" (Ctrl+Alt+L) and "Log out" (Ctrl+Alt+Delete) stopped working on just one of the three systems about a week after OS installation. It is a laptop (Dell Precision M70). The problem persists whether I configure the keyboard to be the Precision M series or a standard 104 key PC keyboard.

Testing has proved that I can apparently assign any available key combination to these two actions, but the shortcuts so assigned never work.

Testing has also proved that I can assign the two key combinations (Ctrl+Alt+L and Ctrl+Alt+Delete) to other actions, and invoking the key combinations will cause those other actions to be carried out.

Question:

Obviously this is not exactly a show-stopper, but I am curious. I'd like to understand what's going on here. Can anyone tell me where to look to solve this little mystery? I can see in gconf-editor that the shortcut assignments I make in the Keyboard Shortcuts applet are applied instantly. I don't know where to go from here to find out why the actions aren't executed when they are called by the shortcuts.