Windows 7 x64 hangs when shutting down

[D0natell0]

I've got problems with this system I'm building where it hangs (crashes?) on shutdown.

System:
Motherboard Commell (QM67) LV-67HTXD
CPU Intel Core i7-2620M
RAM 2x 4GB, DDR3, 1333MHz, Kingston
PSU MiniBox M2-ATX-HV

1. The problem only appears in Windows 7 64 bit
2. Clean start and shutdown in Win XP - implies software issue not hardware
3. I haven't tried Win7 32bit yet.

Here's some details of my investigation so far:-
All of these tests failed to solve the problem.

Unplugged all devices.
Fresh install
Added manufacturer base drivers.
Windows updates applied
Safe mode
Windows clean start
only one memory slot filled (both slots)

In desperation I've created a trace file (using this article Gathering a Startup, Shutdown, Sleep, Hibernate, or Reboot Trace - Windows 7 Forums)

Here's the links to the trace output:
https://docs.google.com/open?id=0B4rN34R0_QVjUktHTE14QVlPMWs
https://docs.google.com/open?id=0B4rN34R0_QVjM05XSEV1b0JiZGc

Please help!

 

[D0natell0]

Here's a link for the 1st (large) file zipped up:
https://docs.google.com/open?id=0B4rN34R0_QVjTGtwVXJNRHByOTA

Sorry for any inconvenience!

 

[D0natell0]

bump

 

[cluberti]

You're probably not going to like this, but according to your shutdown trace, Windows itself took 4.2 seconds to shut down. How long does it take to shutdown, and what do you see on screen (and for how long) in this case?