Horizontal lines on screen and is not clear - ubuntu 12.04

Q : Installed ubuntu 12.04 desktop version on Pandaboard as OS. The screen is having horizontal lines and is also not clear but taking screenshots and see them in other desktops, the screen in the pictures are very clear and are not showing this problem.

A: This may be due to tearing. Try to use a lower resolution. Screen shot will be clear as it takes copy of the framebuffer (available in RAM) and not from the monitor.

Thanks : ILUGC