[arch-general] Unable to shutdown recently (not always)

[XeCycle]

Hello, recently I'm experiencing shutdown problems.

I installed everything (except /boot) on LVM, using LXDM as the
display manager and sawfish as the window manager.  Usually I
cannot shutdown, the computer gets stuck --- wallpaper is still
there, panel is gone, so does other windows; the HDD LED may
flash sometimes; neither NUM LOCK nor CAPS LOCK is responding.
So I need to press the power button to force a shutdown, and, on
next boot, filesystems will be recovering journal, looks like it
got stuck before the filesystems unmounted.

But this doesn't always happen to me, usually if the computer is
used for a long time it will; but if I want to test what is the
cause, i.e. startup -> do sth. -> halt, I cannot yet figure out
what is the problem.

This is my rc.conf (comments grepped out):
--8<---------------cut here---------------start------------->8---
LOCALE="zh_CN.UTF-8"
DAEMON_LOCALE="no"
HARDWARECLOCK="UTC"
TIMEZONE="Asia/Shanghai"
KEYMAP="us"
CONSOLEFONT=
CONSOLEMAP=
USECOLOR="yes"

MODULES=(acpi-cpufreq cpufreq_ondemand tg3)

UDEV_TIMEOUT=30

USEDMRAID="no"

USEBTRFS="no"

USELVM="yes"

HOSTNAME="XeCycle"

NETWORK_PERSIST="no"

DAEMONS=(syslog-ng dbus @crond @networkmanager)
--8<---------------cut here---------------end--------------->8---

Thanks for any help.

-- 
Carl Lei (XeCycle)
Department of Physics, Shanghai Jiao Tong University
OpenPGP public key: 7795E591
Fingerprint: 1FB6 7F1F D45D F681 C845 27F7 8D71 8EC4 7795 E591
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