I understand that your system shuts down immediately when you press the power button.
Unfortunately there is no option to set the period of time that you press to turn off the system.
Maybe Intel should reconsider this "immediate power-off"-feature for future mainboards...
For my part, I have to a put a lag-element inbetween the power off button an the mainboard to prevent unintentionally switch-offs.
Is there somebody with a better idea?