This is the error in the log:
codepage_initialise: called twice - ignoring second client code page = 737

Here is my smb.conf:
[global]
workgroup = UAF
netbios name = LINUX
server string = Samba
log file = /var/log/samba/log.%m
load printers = no
log level = 10
max log size = 50
name resolve order = lmhosts host bcast
dns proxy = No
bind interfaces only = True
interfaces = eth0
hosts allow = 192.168.0.
security = user
encrypt passwords = yes
smb passwd file = /etc/samba/private/smbpasswd
socket options = TCP_NODELAY SO_RCVBUF=8192 SO_SNDBUF=8192
local master = yes
preferred master = yes
client code page = 737
character set = ISO8859-7

[backup]
   path = /home/backup
   username = backup
   valid users = backup
   read only = no
   directory mode = 0700
   create mode = 0600
   only user = yes