F9, F8 periodicially hanging upon user login, dbus zombie process, etc.

[Cameron Mura]

Hello,

I'm experiencing a problem on both F8 and F9 (mostly playing on F9 now) 
that I can't seem to get to the bottom of: In several different 
instances of vanilla installations of both F8 and F9 on Dell 
workstations (Precision 490, T3400, etc.), I find that the machine works 
fine for about 1 day, then -- the next day -- hangs at a black screen 
when a user tries to login. This is with both i386 and x86_64 installs.

Gnome is the default disp. manager, and if I remotely access the machine 
(ssh as root) while it's in this frozen state, I see that dbus-launch 
(user 'gdm') has fallen into a zombie state.  Re-booting solves the 
problem, but then it arises again the next day.  I should mention that 
the regular (non-root) user accounts are set-up via NIS/NFS. (I ran 
across some things online regarding problems with pulseaudio and nfs 
users, but this doesn't seem to be it.).   Other suspicious behavior 
that seems to (maybe) be correlated is that launching into a bash shell 
(for, say, a tcsh-based user) results in a stream of infinite /dev/null 
errors (don't have the exact output string in front of me, but can 
provide that later if helpful)... This can be interrupted (ctrl-c) to 
yield the shell.  Further inspection shows that the perms on /dev/null 
are only rw for root (not 0666 or whatever they ought to be...?).  I 
don't know if these two things (1: login screen locking/zombie process 
2: screwy /dev/null perms) are related.

I'm wondering if anyone's seen anything like this, or might have some 
idea as to what's causing it? If so, please let me know, or feel free to 
redirect me to any info about this online (I've spent many hours 
google'ing for it, tweaking config files, applying different sets of 
updates, etc...).

Thanks for any help,
Cameron


PS. This is also at 
http://forums.fedoraforum.org/showthread.php?p=1061369 . Any help / tips 
/ advice would be most gratefully appreciated.