Problems mapping a drive from Vista, Vista employs NTLMv2 as the default

Problems when attempting to map a drive from a Vista/2008 system to another Windows system or to a Samba shared directory

You may encounter problems when trying to map a network drive or when trying to access a shared drive through Windows explorer from a Wndows Vista system. The problem is frequently exposed as a failure to authenticate when entering a vaild user/password combination. This problem is probably due to the fact that Windows Vista and Windows Server 2008 use NTLMv2 as the default authentication level for network security.

Unfortunately, there is not an error or informational message that advises you of this. All that happens is that after you enter the user/password, the credentials box reappears as though you have entered incorrect information.

To work around this, you can set your system to try earlier versions of the LAN Manager authentication, those that may match what the target system can negotiate with, and use the newer NTLMv2 when available. To do this:

Follow Control Panel > Administrative Tools > Local Security Policy > Local Policies > Security Options

Find the entry for
Network Security: LAN Manager authentication level

Change the vaule setting from
Send NTLMv2 response only
To
Send LM and NTLM - use NTLMv2 session security if negotiated

The change should take effect right away.