Windows 7 64 bit / Stardock Fences
This solution worked for me!
Problem
Moved a Fence too far down on the screen, and it disappeared.
Solution
Actually the missing Fence is there, but it's covered up by the Windows taskbar.
1) Move the windows taskbar from it's position at the bottom of the screen to the side position.
2) The top of the missing fence will be visible now and can now be pulled back up to a normal location on the screen.
Note: To move the Windows taskbar
1) Right click the Start button
2) Choose Properties > Taskbar > Taskbar location on the screen > Left