1 Click & Lock 2.91 

1Click & Lock up is a system tray security utility you can use to secure your desktop when you step away from your PC. It's secure and very easy-to-use. Just define a password, and select Lock to hide and deny access to your desktop to anyone without the proper password. You can set the program to launch automatically with Windows, lock your desktop from the system tray, log access attempts, and apply a custom background image. When enabled, it even allows visitors to your PC to leave messages for you. The cold-boot protection and disabling boot keys gives maximum protection that's difficult to get around.