My first Mac: 2011 27" iMac 3.4GHz, 4GB, 6970M 2GB, 256SSD + 1TB HDD. Preinstalled with Lion. I am one of the victims of the system freeze issues after resuming from sleep and playing a video, whether it be Youtube, iTunes, or QT. Only way to recover is to hold down the power button. So, I'm preventing my iMac from going to sleep and I play a youtube video earlier and this is what I get (notice the menu bar, dock icons, and dock indicator lights. It just works... LOL.