My buddy plays Java & Flash based internet games.
Sometimes his poker game will throw up a window in FireFox that just WILL NOT go away so I setup an Xkill icon for him to nuke these annoying windows from time to time and it has worked very well for a year.
Well today he must have missed the window & nuked his desktop and since that time all he has is the top toolbar & a black desktop with no icons.
I tried these remedies via Team Viewer, since he's 25 miles away.
Updated via synaptic, no change.
Uninstalled & reinstalled Task-XFCE, no change.
I had him log out & log back in under my profile, no change.
I'm out of ideas.