Please also add the passwords of the users from both Windows and Linux Box into the "smbpassword" file on your linux box. It would be like this if you have two users having passwords "xxxx" and "YYYY" ..then... use the following commands to accomplish this
# Locate "smbpassword"
it will show you where the "smbpassword" is on your system
Go to "smbpassword" file by CD
Then Vi "smbpassword"
Add the passwords as "xxxx", "YYYY"
Press Esc button on your keyboard
Press "Shift :" on your Keyborad
type wq and then press enter
Restart the "Smb.conf" file from the command line
and then try to access the samba shares from your Windows system.....
Please let me know if this helps.....