WinRAP

RAP (Windows Running Applications Protector) is a handy tool that lets you automatically hide any window or application to prevent unauthorized access. This application can be very useful in situations when you need to leave your computer running so it can complete a particular task, but you don't want anyone to know which applications are running and which ones aren't. The application will display all the currently active processes so you can hide whichever ones you want to keep from prying eyes. WinRAP also lets you set up a password. That way, only the computer administrator can choose which applications and windows to hide. WinRAP doesn't require any installation and is completely free.