Desktop Icons

My desktop suddenly has a single icon (which is one of my application icons) superimposed on top of most all of the normal icons. When I click “refresh” the normal icons are exposed, but then the rogue icon again covers it. On re-boot, the normal icons are displayed when the desktop is first displayed, but as the boot progresses, the icons are again covered. If I go into msconfig and disable the “system ini” file, all normal icons displayed but have been unable to isolate the cause further.