Can not access shared folder

Have problem on accessing the shared folder, envorenment discription:

Host:

1. Windows Server 2003, IP 192.168.0.50.

2. Created a local account "sales" with password.

3. Shared folder "c:\sales", added accounts "sales" into permission and

security container with full control right, also, removed "everyone" from

permission container.

4. Enabled "allow empty password" option at the "local security policy"

5. Disabled "Guest" account.

Client:

1. Windows XP Pro, IP 192.168.0.136

2. Changed the network access style to "Classic" at "local security policy"

3. Clean stored username and password for site 192.168.0.50

Problem:

In the past, click Start --- Run -- \\192.168.0.50, there's a popup window

asked for username and password, input the "sales" account, then, I can got

into the shared folder.

But now, it's failed, when I click Start -- run \\192.168.0.50, there's no

popup window, but an error message says \\192.168.0.50 is not accessible,

You might not have permission to use this network resource...

What happend?

Thanks in advance.

Chuck