Not really on topic for this newsgroup, which is for questions about
Microsoft Access, but as the answer is quite short, I'll answer it anyway
....
The following description applies to Windows XP, there may be some
differences in other versions of Windows.
Right click an empty part of the taskbar and look at the 'Lock the Taskbar'
option on the pop-up menu. If it's checked, uncheck it, otherwise leave it
alone.
Now click and hold down the left mouse button over an empty part of the
taskbar, and drag the mouse down to the bottom of the screen. Release the
mouse button, and the taskbar will move to the bottom of the screen. If you
like, you can check the 'Lock the Taskbar' option now to make accidental
movement less likely in the future.