All of a sudden my Macbook Pro has decided to open Finder on boot up instead of Desktop, leaving me with no menu Bar or Dock. It's no big issue as it can be worked around by hitting CTRL + Left arrow but it irritating not knowing why and what might cause it. Therefore, I would appreciate any input as to a reason and resolution. At present I'm running Mountain Lion - Mavericks OSX 10.9(13A603)