Windows don't clear from desktop!

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http://askubuntu.com – I have recently had my xfce desktop stop clearing windows when the window is closed. The window's image remains on the desktop, as if it were still open. If I drag the window to a different location, the ghosting from the move remains on the screen. The 'Application Menu' has also stopped working. I've reinstalled xfce-desktop with no effect. Any clues as to the etiology of the problem? Any solutions? (HowTos)