Hi, I have a Win XP Pro with all latest Windows updates. I will give the specs later if necessary... but will start with a description to see if anyone has any suggestions or similar experiences. The computer is networked in my office and is randomly shutting down about every other night on its own, unexpectedly. The power light on the case indicates that it is on, however it is not. The actual system does go down (so it's not the monitor) because the services running on that machine are inaccessible from other machines on the network when this happens. Nothing is dumped to the event logs - nothing goes through a shut down process and there are no logs to help diagnose this. The power supply is new and 350 watt, which should be plenty. All the fans are going. The only thing that jumps out at me is that we run a retrospect backup of the machine each night - the backup appears to be in the middle of running and then when it changes drives it logs that it can't locate the drive to back up. So apparently between backing up 1 drive and moving to the other, this happens. But it's not consistent, it backs up successfully some days. Could it be overheating during the backup? If so, how can I test or notice that? Any thoughts are appreciated. Thanks in advance.