Theme changes

[CJ Tres]

I'm at a loss to say what program I have installed that may have started 
this behavior but for some reason, on occasion, the look of my desktop 
changes of it's own accord when I click on the panel.

First I'm seeing this:

[IMG]http://i43.tinypic.com/2chktw1.png[/IMG]

which after an innocent click, suddenly becomes this:

[IMG]http://i41.tinypic.com/snfmfd.png[/IMG]

Clicking on System>Preferences>Appearance changes it back without making 
a choice, in fact even before the window opens to make a choice.

What could be going on?