My desktop icons scramble when using external monitor
I have started plugging in an external monitor to my new Macbook Air. The icons on the desktop automatically reset when I plug in and I've tried putting them back in place but they just reset again when I unplug the monitor and later plug it back in.
Is there any way to prevent this? It's definitely lowering my productivity.
MacBook Air, OS X Mountain Lion (10.8.4)