Comment 63 for bug 351990

Have you ever get a look of this bug report?
https://bugs.launchpad.net/ubuntu/+bug/368461
I've opened it. I think that there are more than one thing that cause
a X crash. I've seen tree type of different crash (maybe four).
As I write in #368461:
(1) system freeze, the screen propose the last seeing, the mouse can
move, pc don't respond with keyboad, ssh on (and safely reboot). This
behaviour is related to this bug
(2) the screen become black and the pc don't respond at all: no mouse,
no keyboard, no ssh (hard reboot). This is related to #368461
(3) just a crash of kdm. Then I can login into kdm-login-interface and
the pc is up.
I've try to catch a backtrace when system crash by installing
libgl1-mesa-dri-dbg libc6-dbg xserver-xorg-core-dbg
xserver-xorg-video-ati-dbg packages but nothing.