Open the “Local Security Policy” manager (can be found in the Start Menu search.

Navigate to Local Policies, Security Options.  Then find the “Network security: LAN Manager authentication level” entry and set it to “Send LM &NTLM – use NTLMv2 session security if negotiated.”.

Alternatively, this policy can be set via the command line:

REG ADD HKLM\SYSTEM\CurrentControlSet\Control\Lsa /v LmCompatibilityLevel /t REG_DWORD /d 00000001 /f

This shouldn’t adversely affect connection to Windows 7+ shares.

Source: http://www.dslreports.com/faq/16438

Update:

The setting above causes problems when attempting to connect to a remote desktop through a remote desktop gateway server (running Windows Server 2012 R2).  It must be set to the default “Send NTLMv2 Only”.

This policy can be set via the command line:

REG ADD HKLM\SYSTEM\CurrentControlSet\Control\Lsa /v LmCompatibilityLevel /t REG_DWORD /d 00000003 /f