Not big, but annoying problem.

The matter is this. Sometimes when the Internet or programs like notepad++. Stupid the screen goes blank and the speakers buzz as the darkness. It happens rarely, but neatly. Especially when lines 5000 to fix, but you can start from the beginning. Thus if to launch something, to mount for example and collapse the window, then plow all the infinite failures. But when the whole day falls a shovel it does not roll at all. What can anyone suggest?