There are many window hiding tools available on the Internet that allow you to hide all open windows with a hotkey, but some do not offer the password protection feature to restrict access. this is where Freeware UltraHide application will come in handy, this application allows you to hide any window with a hotkey and also allows you to password protect that hidden window so that anyone has to enter the previously set password to unlock it.
Launch the app, set the password to unlock hidden windows, by default 123 is set as password, if you don’t want to use the password, leave the password field blank. Once the password is set, click on “Hide UltraHide in tray”.
Now click on any window you want to hide from your boss or relatives using the Alt+Ctrl+Spacebar, UltraHide hides this window in the system tray. To access it again, double-click its tray icon and enter the password.
cons: This program does not allow to define custom hotkeys where user may feel the hotkeys Alt+Ctrl+Spacebar very inconvenient to use.
UltraHide works on Windows XP/Vista/7.