关于samba的问题（很奇怪啊！！！！！）

我的smb.conf的部分内容是这样的
[global]

# workgroup = NT-Domain-Name or Workgroup-Name, eg: MIDEARTH
workgroup = birdhouse

# server string is the equivalent of the NT Description field
server string = Samba Server

# Security mode. Defines in which mode Samba will operate. Possible
# values are share, user, server, domain and ads. Most people will want
# user level security. See the Samba-HOWTO-Collection for details.
security = share
netbios name = linux
...............................................
[tmp]
comment = Temporary file space
path = /tmp
read only = no
public = yes

[public]
comment = Temporary file space
path = /home/sambatest
read only = no
public = yes
大家可以看到，我的samba服务登录的方式是share，我共享的两个目录［/tmp和/home/sambatest]下的配制是一样的，还有它们在系统里的权限分别是这样
drwxr-xr-x 18 root root 4096 06-02 22:02 tmp
drwxr-xr-x 2 root root 4096 06-02 21:52 sambatest
当我从winxp登录到linux时，可以看到tmp 和 public 两个目录，问题就在这里，我可以进tmp目录，但是进public时却进不去，系统提示说无法访问，没有权限使用网络资源！！！这是怎么回事啊