Help with messed up F11 SELinux

[Steve Blackwell]

I've always had problems with SELinux but I set it to permissive and
moved on. Now I want to see if I can fix it.

My logwatch report gives me 20 or 30 lines of :

NULL security context for user, but SELinux in permissive mode,
continuing ()

in the cron section. Then I looked in /var/log/dmesg and I see this
line:

SELinux: 8 users, 12 roles, 2527 types, 119 bools, 1 sens, 1024 cats

System->Administration->SELinux Management, select SELinux User, shows
8 SELinux users: 
guest_u, 
root, 
staff_u, 
sysadm_u, 
system_u,
unconfined_u,
user_u
xguest_u

OK, that looks good but when, as root, I run:

# semanage login -l

Login Name             SELinux User           MLS/MCS Range            

__default__            unconfined_u           s0-s0:c0.c1023           
root                   unconfined_u           s0-s0:c0.c1023           
system_u               system_u               s0-s0:c0.c1023  

hmmm... only 3 users. It this a problem or is it telling me that only 3
SELinuux users are currently in use (ie assign to any Linux user) 
because I'm running in permissive mode?

How can I find out which user has a "NULL security context"?

Thanks,
Steve