KN1 startup problem

Hi there,
I just assembled my new KN1 system and nearly everything works fine.
The only exception is the fact that when I shutdown the system by
pressing the power button or using the option in WindowsXP I cannot
restart the system again by just pressing the power button. All that
happens is a short flash by the power LED and nothing more. This happens
as often as I press the power button.
The only solution to start the system again is to switch off the power
supply, wait a moment, switch it back on an then press the power button
again. When the system starts the BIOS posts that it is running in "safe
mode" and that I have to check the CMOS.
I am using a "be quiet, dark power pro 530W" power supply.
Hope somebody can help!
R