vuid.tdb grows very fast to a very large file

[A. Pohl]

I have Samba_TNG 2.5 with 20 users.

the file samba/var/locks/vuid.tdb grows to 10 MB in 3 hours!
In 2 days to 200 MB!!!
Then the PDC is unreachable. :(
What is wrong here? 

Thanks,

Andreas


smb.conf:

[global]
guest ok = no
security = user
encrypt passwords = yes
smb passwd file = /usr/local/samba/private/smbpasswd

workgroup = VEGU
server string = Samba %v auf (%L)
domain logons = yes
domain group map = /usr/local/samba/lib/domaingroup.mapping
os level = 34
local master = yes
preferred master = yes
domain master = yes
logon script = %U.bat
logon path = \\hera\profiles\%U
logon drive = H:
logon home = \\hera\%U
printer driver file = /usr/local/samba/print/printers.def
wins support = yes
name resolve order = wins lmhosts hosts bcast
dns proxy = yes
time server =yes
dos filetimes = yes
fake directory create times = yes
dos filetime resolution = yes

log level = 0
max log size = 5000
debug timestamp = no
syslog = 0

socket options = TCP_NODELAY 
dead time = 15 		; Default is 0
getwd cache = yes
hosts allow = 192.168.1. 192.25.229. localhost
interfaces = 192.25.229.243 \
		192.25.229.244 localhost
bind interfaces only = yes

follow symlinks = yes
wide links = yes
map archive = yes
map system = yes
map hidden = yes
9-1

[netlogon]
comment = The domain logon service
path = /home/netlogon
;public = no
writeable = yes
browsable = no

[profiles]
comment = Benutzer-Profile
path = /home/profile
create mode = 0600
directory mode = 0700
writable = yes
browsable = no

[install]
path = /home/install
comment = Installationsdateien
;nicht sichtbar
browsable = yes
writable = yes
valid users = @root @edv
create mode = 0760
directory mode = 0770
force user = nobody
force group = root