ActiveScreenLock 1.1 is an easy-to-use (though, very effective) security utility, that allows you to keep others from accessing your system while you're away. It uses password protection, blocks task manager (CTRL+ALT+DEL), ALT+F4, ALT+TAB shortcut and Win key. All attempts to access are logged. ActiveScreenLock can show wallpaper and clock. You can set transparency for ActiveScreenLock window, if you're using Windows XP/2000.