I've seen similar things occur in the past and over time. One example, when in the script editor, a listbox that suddenly appears in the middle and on top of the code, containing data from another running application, when moving the script editor window, it even followed. It had something to do with windows out of certain resources, because when seeing things like this, windows was on the brink of a reboot need, quite unresponsive despite low cpu usage, icons or whole toolbars that disappear, or for example a help window that has lost its treeview control with unability to restore it, shrinked windows and unable to drag them bigger.
