A number of users are reporting an occurrence of an ongoing display issue that appears to be primarily affecting Penryn-based MacBook Pro laptops. According to MacFixIt, the problem manifests itself in the form of alternating light and dark vertical bands which appear on the screen when the notebook wakes from sleep.

The problem is easily resolved on a temporary basis but occurs repeatedly for most of the users reporting the issue:

One account on the Apple Discussions board from user "Atomic Wedgie" reads as follows:

"...every so often, when I wake the MBP (Penryn) from sleep, I see alternating bands of light and dark vertical "stripes" along the screen. It looks as if half the LED backlights did not activate."

The issue doesn't appear to be related to Mac OS X's graphics drivers, as the issue does not manifest itself when the notebook is booted into Windows under Boot Camp.

Reports have indicated that Apple is aware of the problem and working on a fix, which may be released as part of the anticipated Mac OS X 10.5.3 update or as its own firmware update.

Fixes for the problem include the following:

-Press control-shift-eject, which forces the display to turn off and reset. This has been the most straightforward fix so far.
-Put the computer to sleep (From the apple menu or close the lid), wait for the computer to sleep, and then open the lid or press a keyboard button to wake it from sleep.
-Restart the computer.

If you've seen this on your end or discovered another fix or workaround, let us know over in the comments or forums.