Why do my Windows 7 Desktop Icons keep moving ?

Running Windows 7 Professional 64b, on Lenovo T520 laptop , with docking station and LCD screen attached. Desktop is on Laptop not attached LCD.

I have tried every screen setting and combination possible with out success. What seems to be totally random in time and actions, my desktop Icons for no apparent reason all move to the right .

Can anyone explain this and suggest how keep the icons where I place them?