Desktop Icons move to edge of screen

I have a user that is using a MacBook Pro running OS 10.8.5 on wireless. She has complained about her Desktop icons moving to the edge of the screen at random times. It can be a weeks between issues, but this is beginning to become a real inconvenience for her. I took the laptop and went to different area of our school and I was unable to replicate it.

Does anyone have an idea as to what may be causing this?

Much Thanks

Jim W.