When using some applications (LibreOffice, Chrome) it happens that screen flicker (just for a second, or even less than a second) or screen turns into black and then back to normal again... it all happens very fast (usually when clicking with the mouse)... for example, I was searching something in google chrome and list of possible results appeared - when I double click on the search text area (not list of possible results) screen flicker... or when changing border lines in LibreOffice Calc... I managed to create screen shot while using LibreOffice Calc. I am using Nvidia 313 drivers-updates on Ubuntu 13.04. What could be the problem?