desktop disappears when user logs in

this has happened twice now. we take a users pc for maint, user logs in on a different pc to work on for a little while,we get users pc back to them and they dont log off the pc they were working on and log into their pc that we have returned to them and when they log onto their pc the icons on their desktop disappears. several people can log in under thier log in and see the icons on the desktop but the user whose pc it is cant. they cant see my computer icon, network neighborhood, etc it seems stuck on "view as webpage" and "hide all icons when viewed as a webpage". Help!