I have had the hardest time getting Windows to access user level protected Samaba shares until today. I found out how to properly add a samba user (webmin does not seem to do it properly on it’s own). I am using Ubuntu 12.04 LTS.
(replace SAMBAUSERNAME with the name you want to use)
sudo useradd -s /bin/true SAMBAUSERNAME
sudo smbpasswd -L -a SAMBAUSERNAME
sudo smbpasswd -L -e SAMBAUSERNAME