I'm a student using Mathematica on a 2012 macbook pro with OS X Yosemite. Mathematica was running fine on my computer for a long time - one day, seemingly randomly, a blank screen started appearing whenever I open Mathematica. It makes one desktop on my computer (wherever the Mathematica start up screen is) unusable, and it makes it hard to close Mathematica notebooks because when you exit full screen, the notebook goes to the unusable desktop. Screen shot attached. Whenever I quit Mathematica it also always asks if I want to save the changes made to any random Mathematica notebook on my computer, even if I open and quit Mathematica without making any changes to anything. I can work around it, but it's certainly annoying.
This started happening when I was running on Mathematica version 10.0.1.0. I updated to 10.0.2 and it solved the problem for a couple days, then one day when I opened Mathematica it started again. Has anybody encountered anything similar to this, or does anybody have any ideas of solutions?
Any and all ideas would be greatly appreciated - thanks a ton!!