Did you add yourself to samba users?
You can try this GUI to configure it: system-config-samba
I did this to configure mine:
Preferences > Server settings > Basic: input your Workgroup
Preferences > Server settings > Security: Authentication Mode=User, Guest Account=No Guest Account
Preferences > Samba Users > Add user:
Choose a Linux account (the one Samba will use when accessing the shared files. Usually, you want to choose yourself.)
Type in a user name and a password (does not have to be a real windows account or password, its just the input that Ubuntu will ask when someone tries to access the share. It can be "aaa" / "bbb")
So, basically, sharing folders involves two different authentications: first, the one that SAMBA, via SMB protocol, asks for from anyone that tries to access a share. That's step 2 above. Then, after Samba grants that person rights to access the share, Samba itself will need OS authorization to access to the filesystem and its files (the Linux owner-group-world security model). For that, Samba uses the user selected in step 1 above. So any folder (and files) you share must be accessible, inside Linux, by the user selected.
In the Windows world it works the same: there's the share authentication and the NTFS one.
Last but not least: whatever user you select (usually yourself), make sure that it has the Share Files with the Network privilege in Administration > Users and Groups > Advanced Settings button > Privileges tab. I think Ubuntu already grants this privilege to the first user it creates, but it doesn't hurt to check it out.
Also, to share folders, I don't use this GUI, I use Nautilus:
- Right-click the folder you want to share
- Select "Sharing Options"
- Give the share a name, and select read/write or anonymous access
Hope that works for you too!