Sentry - Version 2.2 Sentry is a computer program that can instantly "lock down" your computer on demand, so it stays secure even when you aren't using it. You can customize the appearance of your screen while Sentry is running with graphics, and have your favorite screen savers run within Sentry. Sentry can even take messages from people who dropped by your workstation while you were away. Sentry is ideal for people in workplaces, who may have to leave their system unexpectedly, and don't want co-workers to snoop around in their files. It's also great for teachers, parents, etc, who don't want the kids messing with their computers if it's left unattended.