Computer won't turn off

[teriba]

Setup:
Intel C2D E6600
ASUS P5K-E
2GB Mushkin HP2-6400
EVGA 8600 GT Superclocked 256MB
Seagate 7200.9 200GB SATA
Antec TruePower 2.0 550W
XBOX 360 HD DVD Drive
Silverstone Lascala LC-20
Windows Vista Ultimate

I just swapped the motherboard/CPU/RAM in my HTPC and I now have a weird issue. When I shut it down, either from the Start menu or by pressing the power button on the front, it shuts down properly, turns off and then 2-3 seconds later it turns back on.

So far I have:
- disabled reboot on BSOD
- reversed the power switch connection to the motherboard
- made sure all of the "Power on when....." BIOS options were disabled
- updated the BIOS

Any other ideas?

 

[RadiclDreamer]

Bios flash? Typically this sort of thing is a power supply issue from my experience

 

[robisbell]

driver mismatch.