This is a workaround for making Windows 7+ play nicer with XP dominant environments.

Navigate to: Administrative Tools > Local Security Policy > Local Policies > Security Options

Change the following options:

Network security:Minimum session security for NTLM SSP (including RPC based) Clients Properties

• Uncheck both items on first tab
• OK

Network security:Minimum session security for NTLM SSP (including RPC based) Servers Properties

• Uncheck both item on First tab
• OK

Network Security LAN Manager authentication level Properties

• Choose from drop-menu: ‘Send LM & NTLM and use NTLMv2 session security if negotiated’
• OK