I am getting random shutdowns of my FC4 box, sometimes it just seems to go off (nothing in /var/log/messages) other times it enters a shutdown state.

The last 2 times, the last few things appearing before shutdown starts are some audit messages:

Dec 4 15:42:01 hive crond(pam_unix)[9647]: session opened for user root by (uid=0)
Dec 4 15:42:14 hive crond(pam_unix)[9647]: session closed for user root

Dec 4 15:42:17 hive kernel: audit(:0): major=252 name_count=0: freeing multiple contexts (1)
Dec 4 15:42:17 hive kernel: audit(:0): major=113 name_count=0: freeing multiple contexts (2)

Dec 4 15:42:17 hive gdm[3244]: Master halting...
Dec 4 15:42:17 hive shutdown: shutting down for system halt
Dec 4 15:42:17 hive init: Switching to runlevel: 0
Dec 4 15:42:19 hive dbus: avc: 5 AV entries and 5/512 buckets used, longest ch
ain length 1
Dec 4 15:42:19 hive gpm[2762]: *** info [mice.c(1766)]:
Dec 4 15:42:19 hive gpm[2762]: imps2: Auto-detected intellimouse PS/2
Dec 4 15:42:19 hive xfs[2842]: terminating
...

What do they mean?

Any suggestions on how to track the cause of these apparently random shutdowns?

Thanks

Additional note: I am running ganglia to monitor fans & temps and there is no obvious change in temps or fan speeds just prior to it going down.

I still have these random reboots. They are strange. It shutdown last week (sunday morning) and has been ok all week, but today (saturday) it has shutdown twice.

I started monitoring processes, and just before shutdown I see the following appear in the process list:

root 7183 888 0 15:24 ? 00:00:00 udev vc
root 7188 888 0 15:24 ? 00:00:00 udev vc
root 7371 888 0 15:24 ? 00:00:00 udev vc

pid 888 being udevd

then a second later I see

root 7608 1 1 15:24 ? 00:00:00 /bin/bash /etc/rc.d/rc 6
root 7675 7608 0 15:24 ? 00:00:00 /bin/sh /etc/rc6.d/K02cups-config-daemon stop
root 7698 888 0 15:24 ? 00:00:00 udev vc
root 7701 7698 0 15:24 ? 00:00:00 /bin/sh /etc/hotplug.d/default/default.hotplug vc
root 7702 7675 0 15:24 ? 00:00:00 /bin/sh /etc/rc6.d/K02cups-config-daemon stop

Run level 6 starts to shut most things down, including the network.

So, the question is, what is "udev vc" and why does it enter run level 6 and why does run level 6 shut most things down?