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.