Hi All, My iMac (20" core2 duo 5,1) running a fresh install of Snow Leopard 10.6.8 from an external USB disk does not wake from sleep and I have to reboot. I got this error last time: 15/01/13 12:57:31 PM configd Wake: Drivers Failure panic - AC - PEGP HDEF RP01 USB1 USB2 USB3 USB4 USB7 PATA com.apple.message.domain: com.apple.powermanagement.wake com.apple.message.signature: Drivers Failure panic com.apple.message.result: Failure I intend to put this external HDD into my iMac as the boot drive but don't want to do that if there is a problem with the iMac itself. I previously replaced the original 250GB HDD because it was running out of space but the one I put in (a used 500GB SATAII) seemed to have a problem as it went to sleep when it felt like it and I had to wait before it decided to wake up, but after it did wake everything behaved normally for a while. The external HDD I am booting from is the same age and make/model as the current internal HDD (the one that goes to sleep intermittently) both HDD's came out of a failed LaCie 2Big NAS, but they checked out OK before I installed Snow Leopard on them. So, does my Mac have a problem that is now showing worse because my boot drive is now on the USB? Thanks, Dave.