updated 11:45 am EDT, Fri August 5, 2011
Apple still investigating
Some OS X Lion users are continuing to encounter severe graphics-related crashes, according to reports and Apple's support forums. When affected, a person will see a Mac suddenly crash and display a black screen, or else a warning about a kernel panic. A factor in common is that some sort of graphics event is typically taking place; a crash may also happen when a computer wakes from sleep.
Many of the affected computers are said to be 2010 MacBook Pros using GeForce 330M graphics and a Core i5 or i7 CPU, but some of the impacted systems are iMacs. The trouble may lay in Lion's handling of graphics switching, which allows systems to turn on a dedicated GPU whenever extra performance is needed, or go back to an integrated CPU to save power. Forcing a Mac to use one chipset exclusively appears to solve the crashes in some cases. Disabling system and display sleep may prevent wake errors.
Apple has said it is looking into the matter, including taking in crash reports. Any fix has been weeks in the making, though, and there is no scheduled patch release date.