System freezing on logout

Derek Broughton news at
Wed Oct 19 14:10:16 UTC 2005

Richard Querin wrote:

> linux newbie running Breezy. Recently, I started enabling and
> running xcompmgr to get some window shadowing. The shadowing works fine.
> However, now when I try to log out (or reboot, or shutdown) the system
> just freezes. The only way to get out is to do a Ctrl-Alt-Backspace. (I'm
> not even sure what this does, although I remember reading it somewhere !!)
> This takes me to the login screen from which I can choose
> 'Action->Shutdown, Reboot, whatever.

"ps ux" from a console will probably give you a hint what's hanging you up,
but not necessarily how to stop it.  Try alt-tab, or
ctrl-alt-f1/ctrl-alt-f7 - one time I had something like this happening and
there was actually a window waiting for input, that always opened under
everything else.
> So that is problem number 1. I can't shut down normally. Problem 2. is
> that if I get to the login screen by doing the Ctrl-Alt-Backspace and then
> log in again from there, the desktop comes up but the top panel comes up
> and then immediately disappears, taking the menus, launchers, and clock in
> the panel along with it. Leaving me without any option of using the menus
> for anything (like shutting down, launching programs etc..).

Well you could try saving the current desktop session before you kill the
display manager (which is what ctrl-alt-bs is doing).  I presume you're in
Gnome, and I don't know how you'd do that in gnome.
> Any ideas? Is this stuff related to using xcompmgr?
> One other thing, when I was trying to get xcompmgr working I tried (as
> instructed) setting it in my startup programs and setting priority of 1.
> This caused the system to boot and then just lock up when trying to launch
> the desktop. So I changed the priority to 50 and it now comes up fine.
> What is the priority number and how should it be set?

I would have thought it best to leave priorities off altogether.  Set it too
high, and it may not let anything else run, set it too low and it may never
get a chance to run (which might explain hanging on exit).

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