Hi John,
You have got the taskbar set to auto-hide. To revert back to normal
behaviour, move the mouse cursor so that the taskbar comes back into view.
Right-click on a blank spot on the taskbar and select 'Properties' from the
menu that pops up. On the 'Taskbar' tab under 'Taskbar appearance', make sure
that the checkbox next to 'Auto-hide the taskbar' is cleared (not selected).
By default, all other options should be selected except for this one. Click
'OK' and your taskbar should remain in view.
Dwarf