I'm not sure I understand what you mean.
You might attach a screenshot:
http://www.computerhope.com/forum/index.php/topic,61232.0.htmlIs it that your taskbar (the bar at the bottom of the screen) is disappearing when its not used, until you move the mouse down to the bottom of the screen?
If so, just right click the task bar, go to "Properties" and uncheck "Auto-Hide"
If you have a child in the house, its common that they do that to "hide" things that are running... (personally, I just think that hiding the taskbar makes it obvious...)
(Thats just a possibility, its a pretty common trend at my school.)