Once every few weeks, my Quad will crash when I'm not using it. It is on most of the day, and when I come back to it, the fans will be spinning at full bore. After turning it off and rebooting, it will boot to the apple logo, then shut down. If booted in verbose mode, it says "syncing disks... killing all processes... CPU halted" and shuts down. If I put it in Target Disk Mode and hook my PowerBook up to it, the PB says the disk cannot be repaired and must be reformatted. Essentially, telling me it's f*cked. Never seen such a harsh disk error before in OSX. The ONLY thing that fixes this problem is when I run Disk Warrior on the PowerBook via firewire. It rebuilds the Quad's HD, and it will boot normally for a few weeks then. Can anyone shed some light on what might be causing this? I am running a single Samsung HD103SJ 1TB Hard drive.