Check your WOL (Wake on LAN) settings. Wouldn't surprise me if they're on and somehow or another the signal to turn the computer on is being sent either erroneously or there's something else going on.
The other option is to simply get a power strip with an on/off switch and flip it to off every time you shut the system down for the night. No power, no boot, simple as that.
I am using Windows 7 Pro and am restoring everything after a reformat of my HD. For some reason that escapes me, the Desktop restarts at 6AM without my input or intervention.
I have checked the Windows Update,, Task Scheduler and and all my currently installed apps. Also, I manually "Shut Down," not Sleep or Hibernate. And the unit (Dell XPS 410) is definitely off before I go to bed. I found nothing in the BIOS that allows for a timed start in any way.
Any suggestions? I am open to all...