Hi guys, from yesterday my iMac started to have an annoying problem, If I put him in Stop•Sleep, when I push a button to wake him up, he won't start, the fan starts but the screen is black and its like blocked. Same thing if I turn off the screen, but he's running, after some time if I push a button or move the mouse to turn on the screen, he's freezed, blocked, the fun are running but the screen remain black. Then today, he block himself during while I was posting on a forum, so when he was on. I checked the HD and other stuff with Onyx and everything looks fine. One month ago I updated to 8GB of ram from Crucial, don't know if this could be the problem, but until yesterday I had no problem and no Kernel Panic at all. Now I tried to remove the kit and put the default base 4GB kit.