MacBook screen flickering; MacBook Pro display refresh problems when scrolling

Many Apple laptop owners are experiencing two very prominent display problems. With regard to the MacBook Pro there is a problem with either the display drivers or the graphics processor itself which causes scrolling to not completely refresh the screen, resulting in garbled-looking display output with text and images running into themselves. In addition, some users are experiencing a similar problem where parts of the display that are actively being scrolled will flash in big checkered-like blocks during the scrolling process. This problem seems to only occur in certain applications and not in others. For instance, one Apple Discussion user writes:

Apple Discussions poster plogue87:

"Applications where problem is visible: Mail, iChat, Safari, Firefox 3.0, Finder, iTunes (store only), Stickies...Applications ins which the problem cannot be replicated: FireFox 2.0.0.14 (scrolling only), iTunes Library, Pages '08, iPhoto, Dictionary, TextEdit."

There may be other additional applications where this problem does and does not occur, but perhaps this may indicate that the problem is not hardware base and might be solved in the future with a driver or other software update from Apple. Some users have found temporary relief by reinstalling their operating systems, but others have not had such luck. Still others have found that the problem seems to be less prevalent when the power cable is plugged in. For others, simply logging off and logging back in fixes the problem, or restarting also does the same thing.

Non-pro MacBook owners are experiencing a different display problem where the screen begins to flicker. While unlike the MacBook Pro the display image seems to be just fine, the backlighting mechanism appears to get in a state where it flickers between low and high brightness about 10-15 times per second. This seems to happen more often when users attach their computers to external displays, but also occurs when users slightly dim their displays.

One Apple Discussion user found that this problem seemed to be linked to how the hard drive was connected to his computer. The user removed his hard drive and put into an external hard drive enclosure. Upon attaching it to the computer and booting off it the computer booted normally and the flickering problem disappeared. As such it is very possible this has to do with a power problem in the computer, where components in the machine are drawing power away from the backlight mechanism, resulting in this flickering. While users should not be expected to remove their hard drives and put them in external cases to solve this problem, users may benefit from preventing the display from dimming either before sleep or when running on battery by changing these settings in the energy saver system preferences.

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