http://www.tannerwilliamson.com/2009/09/14/windows-7-seven-network-file-sharing-fix-samba-smb/
Windows 7 Home Premium users, READ THIS:
Windows 7 Home premium users do not have the ability to follow the above instructions, and will instead have to do these instructions contributed by commenter “James”.
FOR HOME EDITION
1 . Open registry editor ( Start search – regedit)
2 . Browse to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa
3. Create a new DWORD value with the following properties:
NAME: LmCompatibilityLevel
VALUE: 1
4. Restart your PC and try the connection again…