How to Fix External Drive Connection Problem in Windows Vista

In default mode, Windows Vista only permits NTLMv2 authentication on a network due to security reason. Certain external drives are incompatible with this authentication type. To fix this problem, LM and NTLM authentications need to be enabled. Here is the method:

1. Click Start button.
2. Select command/search field, type secpol.msc. The Local Security Policy utility will open.
3. Examine the left menu and select Local Policies \ Security Options.
4. Examine the right pane, scroll down to find Network Security: LAN Manager authentication level. Double click on it.
5. Examine the Local Security Setting tab and there will be a drop down menu with several options. Select “Send LM & NTLM – use NTLMv2 session security if negotiated.”
6. Some dialogs will appear. Accept it all.
7. The computer will restart.

Note that this method commonly works in Windows Vista Ultimate. For Windows Vista Home Edition user who is having trouble performing this method, please read on How to Enable Local Security Policy Utility in Windows Vista Home Edition.