Toshiba Satellite C40-B User Manual page 72

To open the Screen Resolution dialog, click Control Panel ->
Appearance and Personalization -> Display -> Change display
settings under Windows System in the Apps view.
If you are running some applications (for example a 3D application or video
playback), you might see some disturbance, flickering, or frame dropping
on your screen.
If that occurs, adjust the resolution of display, lowering it until the screen is
displayed properly.
User's Manual 4-27