If you’re using a shared computer at your home or office, usually you have rules to all users when they’re using computer. The effective way to warning and force them to read your rules is put the message in Welcome Message that shown every time the computer boots-up.

To create a new welcome message is very easy. Modify the registry is not necessary. And here are the steps:

1. Open Local Security console first by click Start -> Run menu, enter secpol.msc on box and then press Enter.

2. Navigate to Local Policies | Security Options key.

3. Find Interactive logon: Message text for users attempting to log on and Interactive logon: Message title for users attempting to log on item.

4. To set the message body, double click Interactive logon: Message text for users attempting to log on, type your message and then click OK to save the message.

5. To set the message title, double click Interactive logon: Message title for users attempting to log on item, type the message title and then click OK button to save the message title.

6. Close Local Security Settings console.

7. If you want to test the message box, just log off or restart your computer. Then, the message box will appear as your first screen.

If you want to remove the welcome message, just empty the Interactive logon: Message text for users attempting to log on and Interactive logon: Message title for users attempting to log on value.
Note: Sorry, I can’t capture the message box appearance, I’ll update it soon.