I leave my computer on all the time, so I like the computer to turn off the monitor after a period of inactivity. However, if I use any screen saver other than the blank screen one, the monitor will not shut off, the screen saver just stays on. It's as though the computer detects the screen saver as computer activity, and doesn't shut down the monitor. Is this nomral? It doesn't make a whole lot of sense to me that it should work this way.