The game just crashed.  This was the standard crashed-while-clicking variety.

What's interesting is there were two crash reports in my folder.  I had seen a strange graphics glitch just before this crash and forgotten to take a screenshot.  Maybe when I closed that game it captured some useful information in the crash report.

Crash:

http://dl.dropbox.com/u/8751953/Elemental0_806-2010-07-13T22-39-03-421.zip

Maybe related to the graphics glitch:

http://dl.dropbox.com/u/8751953/Elemental0_806-2010-07-13T22-33-03-266.zip

The graphics glitch looked like a laser gun fight was occurring between two of my cities.  Then I zoomed out and panned around and saw all of my cities and the nearby goodie huts had these strange lines and particle effects connecting them, blinking in and out.  I saved and exited out.  The glitch did not reoccur when I loaded the saved game.  The city I was zoomed in on at the time it occurred had an Air Shrine, which has a big particle effect at the top of it, so I wonder if that might be related.