I manually put my iMac to sleep before going to sleep myself last night.\nIt's set to do so automatically, but I kept it awake for quite a while, as I\nwas busy doing work. It's also set to wake up at about 8:30 in the morning.\n\nToday I discovered that the iMac was off...somehow, it shut down. There was\nno overnight power outage (clocks still working, no power-failure\nindications on other appliances). I restarted via the power switch (at 10:12\nAM).\n\nAfter the machine booted, it created a log entry regarding the shutdown:\n\nFeb 18 10:12:11 localhost kernel: Previous Shutdown Cause: 3\n\n\nFWIW, later, when my next scheduled TM backup kicked in, it took quite a\nwhile for it to complete its backup. Apparently, there was a need to do a\n"deep traversal":\n\nFeb 18 12:05:06 nicks-imac /System/Library/CoreServices/backupd: Node\nrequires deep traversal:/\nreason:kFSEDBEventFlagMustScanSubDirs|kFSEDBEventFlagReasonEventDBUntrustabl\ne|\n\n\nAny idea what this means?