I have a small network with 11 XP machines and now one Windows 7 Home Premium notebook. The local user accounts on each of the machines matches a user created on the server. All of the XP machines access the shares and the permissions set work fine. some users are limited to certain shares...
The notebook is the problem; I set up a user on the notebook called "user1" with password "password1" and did the same on the server. I also set that user up on one of the XP boxes. When I set up a share to give access to that user the notebook can't and the XP can. When I look at the sessions active on the server it shows the notebook authenticated as "guest" instead of "user1" where the XP shows as "user1" and works fine.
Try this
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...