Recently, my iMac (late 2009, 3.06 GHz Intel Core 2 Duo, 12gig Memory ) has been giving me the White Screen of Death. Ive been able to boot to Disc Utility and restore the computer each time, but its becoming more frequent. I use Super Duper to copy my HDD to an external HD (bootable), and it has set that external HD at my boot drive. Could that be causing my iMac to have problems? Should I go into System Preferences and change my boot drive back to the iMac HDD? Would appreciate any ideas. Thanks.