The status of the NUM LOCK key is specific for each user, and by default, it is disabled. If you want to enable the NUM LOCK key for use before a user presses CTRL+ALT+DEL to log on, you must use Registry Editor to change the default behavior. To enable NUM LOCK before a user logs on, use Registry Editor (Regedt32.exe) to locate the following registry key:
HKEY_USERS\.Default\Control Panel\Keyboard
Change the value of the InitialKeyboardIndicators value in this key from 0 to 2.