Description of problem:

For some reason, gnome-panel is crashing.  While this is annoying and should be
address, the bigger issue is a dialog that appears after restart that says:

--------------------------------------
I've detected a panel already running,
and will now exit.

                               [ OK ]
--------------------------------------

and when you acknowledge this (by clicking OK) it reappears over and over and
over.  In the end, I just hide the window on an unused desktop and continue. 
I've currently got two of these on my desktop (for two crashes) and suspect that
number could easily grow over time.

While it's not great that gnome-panel is crashing (and I'll try to track down
why) it's worse that these messages 'respawn'.