Q: why doesn't my on/off button work after mavericks install?

I installed Mavericks this past weekend and have not been able to shut off my Macbook Pro (Retina Display) since.  The button seems to shut off the display, but the computer itself continues to run.  It apparently goes to sleep after some period of time since the battery seems not to drain.  With Mountain Lion I at least got a warning when I hit that button by mistake to ask if I really wanted to shut it down, but now it just goes.

Does anyone know what is happening and how to correct it?