There are also some other wakeups/power up options. You may have:
Powerup/wakeups on lan
Powerup/wakeups on key press
Powerup/wakeups on modem
Powerup/wakeups on mouse
Powerup/wakeups on «some other event»
Powerup/wakeups at time/day/date
On some rare occasions, like some random electrical glitch, one of those settings could become enabled.
On boot, enter your BIOS setup.
Make sure that none of those are enabled. Deactivate any that is active.
Electro
April 2011