Hello, my parents have a late 2009, 27inch iMac running Lion 10.7.4 They say that ever since they upgraded to Lion they have been experiencing random freezes, slow start up and lagging apps. They took it into the Mac store and they reported nothing wrong with it, wiped it and clean installed Lion again. They brought it home and the same slow downs began to happen again. I have been playing on it and it starts up super slow, opening apps is a nightmare, I have been looking around the forums but haven't seen any solutions to this issue with 10.7.4 Wondering if it has something to do with the graphics card? ATI Radeon HD 4670? Any advice or a point in the right direction would be helpful, thanks!