Windows XP cannot connect to windows 7 shared folder

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