My laptop screen has been flickering whenever I am not charging it. The screen is readable but the brightness of the screen keeps changing from bright to dark very quickly. When charged, the flickering stops. I have tried to change the refresh rate and screensaver power options but nothing works. I am not sure if it is a settings problem or something wrong in the hardware. My laptop is Samsung Series 5 Ultrabook.
You can try updating your graphic drivers, see if that helps...but if this only started happening recently and you haven't made any significant changes to your computer, it is most likely a hardware issue.
If you have a second monitor, try connecting it to your computer. Is the flickering only the laptop or on the 2nd screen as well?