edit:
you can confirm the problem as being a particular service by
run cmd.exe as a admin, run
net.exe start
this will provide a list of the services running
then you can
net stop "the service you want to stop"
then see if your shutdown works as expected, use the quotes around the service name if there is a space in the friendly name.
if it is not that, I would block the card from the network by doing a ipconfig /release command and see if it will shutdown
(a service still may block the shutdown)
sounds like you have a service running that is sharing streaming media and tells the system not to sleep.
powercfg /energy
or the powercfg.exe /requests should show the name.
Streaming media often will block sleep so they can stream to other devices on the network.
Most often fix:
control panel->hardware and sounds->power options->change plan settings>change
this will bring up power options dialog, scroll down to multimedia settings, expand when sharing media
select Allow the computer to sleep, select apply
xero99 :
dodger46 :
xero99 :
Yes, we're definitely making progress. All my drivers are already up to date, i could try rolling the adapter driver back but that might not help.
Perhaps try disabling the Adapter in Networking and Sharing to see if the machine shuts down normally with it off...then you know you're in the right area...
I disabled the network adapters and have been able to perform five successful shut downs in a row! I guess we've probably found the issue unless that was just luck.

Now we could do with finding out how to stop the network adapter freezing the shutdown process while it's enabled?