Try upgrading the security on the NAS if you can. I was having trouble with my SMB shares untill I raised the security to include password encryption. If you can't up the server's security, you can down grade windows' through the local security policies.
Local Policies > Security Options >
1. Network Security: LAN Manager Authentication Level > Send LM & NTLM responses (Win95/98 level)
Send NTLM responses only (early Win NT/XP level)
2. Network Security: Minimum security for NTLM SSP based servers/clients > Uncheck both options
good evening ladies and gents
i have just found a solution that works for me on 2 computers both running W7. it seems windows 7 has basically disabled auto recognition of folders esp at root level.
So with that in mind it is quite simple, all you need to do is map your drive, but importantly, you need to map it to a shared folder on the drive that you have already established and have permission to access. eg \\192.168.1.2\public
Like i say I'm guessing this is a feature from MS to stop you and your network users going where they have not been given explicit permission to do so. that my assumption anyway.
hope this helps
However, SAMBA servers, or certainly the one I have only accept FAT32 file systems.