The problem is Windows 7 uses NTLMv2 and XP/2003 use LM & NTLM. To resolve this issue, do the following on the Windows 7 computer:
- Run GPedit.msc
- Expand Computer Configuration->Windows Settings->Security Settings->Local Policies->Security Options
- Open the properties for Network security: LAN Manager authentication level
- Set the value to: Send LM & NTLM responses
- Run Services.msc
- Restart the Server service
It should be working now...
