I have updated Win 8 to 8.1. I have set desktop background to show in metro UI (start screen). I have extended desktop and on the second monitor after login I have only blue screen

After going to desktop and back to metro (start), then correct background is shown on second monitor as well.
And also same blank blue screen on 2nd monitor is shown when I lock my PC (In Win7/8 it was default black).
How can this be fixed?