Anyone's 2011 iMacs freezing randomly after Lion upgrade? Because mine is. I did a hardware test and resulted in no problems found (I do have Crucial RAM installed, but they never gave me problems prior to Lion install). I also did a repair permissions in disk utilities and it went smoothly, but the random freezing persists. Had to hard reboot twice today. Is anyone else experiencing this, or might have a clue what the issue is? It isn't the 1 TB recall either (I have the base 21", with 500 GB of HD, no SSD).