There are two ways this could have happened. Either you have selected "Relocate Automatically" in the Coherence options screen for your Virtual Machine, or you manually drug the task bar to the top of your screen. To fix this, open your VM's Coherence options screen and uncheck "Relocate Automaticaly" under Windows Task Bar. If that fails to do what you want, then in Windows (when the Windows task bar is visible), click on the task bar and drag it to where you want it (bottom, left, right or top of screen) and let go. Dragging the task bar around is a feature of Windows.