Restricting Logon Access

Step 1.
Open the run dialog box and type the regedit command.
Step 2.
You goto the root key: HKEY_LOCAL_MACHINE\Network\Logon
Create the "Logon" subkey if it is not present on your machine highlight the Network key + right click in the left hand Regedit panel + select New + Key + name it "Logon" press Enter. Then add/modify a DWORD value and call it "MustBeValidated". Double-click it, check the Decimal box and type 1 for value.