Networking :: Samba Username Invalid On This System

I have an ubuntu 8.04 running samba that's integrated with active directory but not using winbind. Things are working fine except there are lot of entries in the samba logs about:

smbd/sesssetup.c:reply_spnego_kerberos(439)
Username CARBYkentoso$ is invalid on this system

CARBY is the domain name and kentoso is the computer name. I only see this error for the computers and not the users. Other than this, it's working fine. Is there a way to make this error go away? This is the smb.conf file:

[global]
workgroup = CARBY
realm = CARBY.LOC
server string = LION
security = ADS
map to guest = Bad User
obey pam restrictions = Yes
passdb backend = tdbsam
pam password change = Yes
passwd program = /usr/bin/passwd %u
passwd chat = *Entersnews*spassword:* %n
*Retypesnews*spassword:* %n
*passwordsupdatedssuccessfully* .
unix password sync = Yes
client NTLMv2 auth = Yes
client lanman auth = No
syslog = 0
log file = /var/log/samba/log.%m
max log size = 1000
name resolve order = dns hosts lmhosts bcast
printcap name = /etc/printcap
disable spoolss = Yes
preferred master = No
local master = No
domain master = No
ldap ssl = no
usershare allow guests = Yes
panic action = /usr/share/samba/panic-action %d
invalid users = root, nobody

[printers]
LOCment = All Printers
path = /var/spool/samba
create mask = 0700
printable = Yes
browseable = No

[print$]
LOCment = Printer Drivers
path = /var/lib/samba/printers

[SHARE]
LOCment = Samba share
path = /share
valid users = @share
admin users = djoe
read only = No