Task bars like to do that! Place your cursor on an empty
part of the taskbar, right-click your mouse and
uncheck "Lock the taskbar". Now place your cursor at the
very top of the taskbar--right where the taskbar line
meets the wallpaper. When you do it correctly the cursor
will change into a line with an arrow on the top and an
arrow on the bottom. When that happens, hold in your left
mouse button and drag the taskbar back down to where you
want it. Then, if you want to, place your cursor on top
of the start button. Don't push the start button, but
right click on your mouse. A screen will come up and you
click Properties. Click the top left tab on the next
screen which says Taskbar. Now check Auto-Hide. From now
on your taskbar will be hidden. To use the taskbar now,
simply move your mouse to the bottom of the screen and it
will pop back up! Don't forget to place your mouse on an
empty part of the taskbar again, right click and "lock
the taskbar" again! Have fun!