No-POST computer has strange symptoms

[El Presidente]

I have the following configuration:

Kudoz 7X/600 VIA Apollo KT600 V1.0
512 DDR 266 PC2100 RAM
Athlon XP 2600+ 333FSB
nVidia GeForce FX5200 128Mb Graphics card
Sony 52x CD Burner
120Gb Western Digital HDD

I just purchased this motherboard and hooked it all up. I hit the power button and immediately the motherboard beeped and 1 second later, the computer shut down.:hotbounce I switched PSU to a 400W model and the same thing happens except the computer stays on for 2 seconds now.:suspiciou The RAM has been verified as working as well as the HDD. I have tried booting without any IDE devices hooked up and the same thing happens. Another interesting issue; once the power button is hit and the system shuts down, hitting the power button again will not turn on the computer. In fact, it does nothing. To turn the computer on, the power cord must be unplugged from the PSU and then replugged. I would appreciate any help you could provide.

Thanks.

 

[El Presidente]

Update

Well, I have given up and I am returning the motherboard and processor to PartsPC for an exchange. However, I'm still curious as to what would cause such a problem. Any info would be nice.