1. Run Registry Editor (regedit.exe). 

2. Go to the following key in the registry: 

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\LSA 

3. On the Edit menu, click Add Value and use the following entry: 


Value Name: RestrictAnonymous
Data Type: REG_DWORD
Value: 1

4. Exit the Registry Editor and restart the computer for the change to take effect. 

Note: It is only possible to control this operation after installing Windows NT 4.0 Service Pack 3 or the Windows NT 3.51 hotfix. 

Key:[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\LSA]
Value Name: RestrictAnonymous
Data Type: REG_DWORD
Data:(0=disabled, 1=enabled)
More info: http://support.microsoft.com/support/kb/articles/q143/4/74.asp