My iMac screen is going crazy when gaming sometimes with MW3. It starts flickering and eventually goes completely black. Also, sometimes on the Mac side it will flicker. Is there a firmware update for the Mid 2010 iMac 27" to resolve graphics issues? I am running the current version of Lion and all updates have been completed as of a few mins ago...all I had was an iTunes update and a printer update. See my System Info and a pic of the iMac screen.