There have been a some reports that followed the release of Mac OS X Lion from iMac users complaining about graphic or video problems.
One user reports that he’s been experiencing video artifacts on his 2011 27-inch iMac configured with a 3.4GHz quad-core Intel Core i7 and AMD Radeon HD 6970M graphics processor with 1GB of GDDR5 memory. It’s been fairly intermittent and it always disappears for a while after a restart.
Today the problem was so different and a lot worse than usual that they finally decided to call AppleCare.
