Alright, first things first. Learn to speak English please. Second, I'm guessing you mean when you take a DOF Screenshot (Ctrl+Shift+P) you are standing there for a really long time?
Depending on how fast your PC is, the time it takes to snap screenshot can vary. In your situation, it can take a while. You can tell if it's still taking a DOF if you see the screen is still shaking somewhat.
Maybe you set the scale factor too high?