Hi everyone, I recently upgraded the RAM on my early 2009 iMac 20-inch and everything worked fine for a day or two. But suddenly this morning it's started to reboot itself. The screen goes grey, then the apple logo comes on and it reboots. Is it a problem with the RAM? Is there any way to check if it is? And if it is, what can I do about it apart from going back to my agonisingly slow 2G of RAM. I have replaced the 2G with 8G of RAM (4Gx2). Thank you!