[lug] Help with window manager "lockups"

[Michael J. Hammel]

I need some help trying to figure out how to get around a problem with
my desktop.  This one just has me stumped.

I wrote about this previously and mistakenly blamed Metacity (though
metacity's reaction to the problem was still bad and was enough to make
me switch to XFce on this machine).  I'm having a window manager
"lockup" that prevents any mouse clicks or autoraise/autofocus from
being honored and keyboard input from allowing me to move between
desktop workspaces.  The problem is intermittent:  happens at what
appears to be random times though lately it seems to happen when I
change workspaces to where Evolution and Firefox are running side by
side in a single workspace spanning dual monitors. I have no idea if
these apps are affecting the problem or not.

The problem happens on just one machine running F9.  That machine has an
NVidia card and is using the NVidia driver (not the open source driver).
Other machines running F9 using other video drivers have not had the
problem.  I've upgraded the NVidia driver to the latest driver with no
impact on the problem.

The desktop is still running - I can pop up windows from other clients
but can't give them focus.  The window with focus does not accept
keyboard input.  I can kill the X server with Ctrl-Alt-Backspace.  The
problem occurs with GNOME (metacity), XFce (xfwm4) and KDE (kdewm).
It's always the exact same symptoms:  no focus change, no keyboard input
except for killing the server.  Panel apps like the clock and system
monitors (with graphs) continue to run.  The mouse also moves freely
around the displayed windows.  There is nothing in the X or system logs
showing any problem has occurred.

Considering the exact same problem occurs with three different window
managers I don't think its desktop or wm related.  It might be the
USB-based wireless keyboard/mouse I use (Logitech S510) but I'd expect
the mouse to stop working completely or the keyboard to not be able to
send the server kill sequence.    It could be the memory in the system
is dying but I'd expect random errors in that case - not the exact same
error each time.

I'm thinking it might be USB ports on this Dell.  I've seen errors in
the system logs from the USB subsystem in the past on this box.  I
suppose a USB hickup left the window manager in a state it can't get out
of, though to have three different window managers hit the same state
seems odd.  There must be a common library at fault here (not recovering
from the USB fault).  I just don't know which one.  And I'm not even
sure if the USB is to blame here.  I'm just running out of other ideas.

I really hate having to kill the server every time this happens,
especially since it's happening about once a day now.  Fortunately
Firefox, Evolution and vi recover from these crashes rather well.  My
next guess is to replace the wireless keyboard/mouse, but the
replacement will *also* be USB so I'm not sure that's going to help any.
There are no PS/2 connections on this box.

Anyone have any other suggestions?
-- 
Michael J. Hammel                                    Principal Software Engineer
mjhammel at graphics-muse.org                           http://graphics-muse.org
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