With out going into my bios at present,i believe there is an option of a setting for startup after a power cut.Will check it out for interest shortly.
The link may help? (next page) or may not.
After power failure (IN BIOS?)sets what you want your computer to do when power is restored after an interruption. You can set your system to switch on and reboot or stay off. Select the former if you want your computer always to be ready and waiting for you. Choose the latter to play it safe, so your computer doesn't keep trying to switch back on during brief periods of power restoration or so that you know the power has been off.